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UNIVERSITY  OF  ILLINOIS  LIBRARY  AT  URBANA-CHAMPAIGN 


L161  — 0-1096 


CARNEGIE  INSTITUTION  OF  WASHINGTON 

Publication  No.  381 


UNIVtni. 


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Of  i  i _ !  I V1 


IQ 
1  .3 


1927 


PRESS  OF  J.  B.  LIPPINCOTT  COMPANY 
PHILADELPHIA,  PA. 


A  GEOLOGICAL  COMPARISON  OF  SOUTH 
AMERICA  WITH  SOUTH  AFRICA 


BY 

ALEX.  L.  DU  TOIT,  D.Sc.,  F.G.S. 


WITH  A  PALAEONTOLOGICAL  CONTRIBUTION 

BY 

F.  R.  COWPER  REED,  M.A.,  Sc.D.,  F.G.S. 


Published  by  the  Carnegie  Institution  of  Washington 

Washington,  1927 


-  . 


CONTENTS 


•TT? 

D  <?  ^ 


PAGE 


Chapter  I.  Introduction .  i 

Chapter  II.  Geological  Framework  of  the  South  Atlantic .  6 

Section  A.  The  western  side  of  Africa .  6 

Section  B.  The  Falkland  Islands .  n 

Section  C.  South  America .  13 

Section  D.  Generalized  comparisons  between  the  two  continents.  1 5 

Chapter  III.  Argentina  and  Bolivia .  18 

Section  E.  The  sierras  of  the  District  of  Buenos  Aires .  18 

Section  F.  The  southern  pre-cordilleran  region .  27 

Section  G.  The  pre-andine  belt  of  northern  Argentina  and  of 

Bolivia .  55 

Chapter  IV.  Pre-Gondwana  Basement  of  Eastern  South  America .  59 

Section  H.  The  Devonian  system .  59 

Section  I.  The  Early  Palaeozoic  beds .  62 

Section  J.  The  pre-Cambrian  formations .  64 

Chapter  V.  Gondwana  System  in  Brazil,  Uruguay,  and  Paraguay .  66 

Section  K.  The  Parana  Basin .  66 

Section  L.  The  northeastern  region  of  Brazil .  94 

Section  M.  Eastern  Brazil .  95 

Section  N.  The  Cretaceous  of  the  interior .  96 

Chapter  VI.  Geological  History  of  the  Afro-American  Land-mass .  97 

Chapter  VII.  Bearing  on  the  Displacement  Hypothesis .  109 

Chapter  VIII.  Conclusion .  118 

Bibliography .  121 

Appendix.  Upper  Carboniferous  Fossils  from  Argentina .  129 

Triassic  Fossils  from  Rio  Claro,  Parana,  Brazil .  150 

Index .  151 


ILLUSTRATIONS 


Plates  I  to  XVI  follow  page  158 

Geological  map  of  part  of  South  America . In  pocket  at  end  of  volume 

TEXT-FIGURES  PAGE 

1.  Succession  on  the  northeastern  side  of  the  Sierra  de  la  Ventana .  20 

2.  Geological  sketch-map  of  a  small  area  along  eastern  base  of  the  Sierra  Chica  de 

Zonda  to  the  south  of  San  Juan .  29 

3.  Section,  about  75  meters  in  height,  in  ravine  north  of  the  Rio  Grande,  Sierra 

Chica  de  Zonda .  30 

4.  An  infolded  patch  of  tillite  in  Palasozoic  beds  close  to  Leoncito  Encima,  Barreal  33 

5.  General  succession  at  Potrerillos .  49 

6.  Section,  10  km.  in  length  through  Taquara,  Rio  Grande  do  Sul,  showing  the 

Triassic  volcanics  resting  on  an  undulating  surface  of  the  false-bedded  Rio  do 
Rasto  sandstones .  91 

7.  Suggested  continental  restoration  under  the  Displacement  Hypothesis .  116 

v 


1 


A  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA 

WITH  SOUTH  AFRICA 


By 

Alex.  L.  Du  Toit,  D.  Sc.,  F.  G.  S. 


With  twelve  plates,  one  map,  and  seven  text-figures 


■ 


' 


CHAPTER  I 

INTRODUCTION 


With  the  passing  of  time  and  the  growth  of  knowledge  there  has 
come  about  a  fuller  realization  of  the  extremely  prominent  part 
played  by  the  ancient  continent  of  ‘  ‘  Gondwanaland  ”  in  the  past 
history  of  this  earth.  It  does  not  detract  from  its  importance  that 
owing  to  lack  of  data  the  limits  set  to  the  land-masses  during  the 
various  epochs  are  not  always  properly  known,  or,  more  correctly, 
the  limits  as  seen  in  the  relics  preserved  in  the  existing  continental 
masses  of  the  globe. 

We  are,  on  the  other  hand,  still  forced  to  speculate  as  to  how  these 
various  sections,  as  we  now  find  them,  were  bound  together  at  the 
beginning  of  the  Mesozoic  and  how  they  ultimately  came  to  be 
parted  by  thousands  of  kilometers  of  ocean. 

During  the  early  part  of  the  century  and  with  the  limited 
knowledge  available,  it  sufficed  to  assume  that  the  fragments,  as 
we  see  them  in  South  America,  Africa,  Madagascar,  India,  Australia, 
and  Antarctica,  were  linked  together  at  some  periods  in  the  late 
Palaeozoic  and  in  the  Mesozoic  by  equally  extensive  land  connections, 
or  else  by  relatively  narrow  “land  bridges,”  which  at  later  stages 
became  submerged  by  the  ocean.  Geological  and  geophysical 
researches  within  the  past  decade  have,  however,  rather  severely 
shaken  our  confidence  in  such  orthodox  views,  which  until  then  had 
commended  themselves  by  their  very  simplicity.  Astonishing  simi¬ 
larities — stratigraphical,  lithological,  and  palaeontological — between 
regions  now  parted  by  ocean  came  to  obtrude  themselves,  becoming 
all  the  more  striking  in  that  the  fossil  remains  contained  in  these 
formations  were  not  marine,  but  entirely  terrestrial.  Almost  identical 
climatic  vicissitudes  and  sequences  could  be  deduced  for  the  several 
sections — glacial  to  start  with  and  arid  toward  the  close — though 
impossible  to  explain  under  current  theories,  followed  by  volcanicity 
on  a  truly  enormous  scale.  Major  tectonic  structures  found  their 
homologues  across  the  wide  intervening  seas.  Furthermore,  the 
marine  Tertiary  deposits  fringing  the  present  continental  masses  not 
only  indicated  how  different  must  have  been  the  distribution  of  land 
and  water  during  that  late  era,  but  hinted  at  an  unexpectedly  recent 
date  for  the  origin  of  the  existing  oceanic  basins. 

The  hypothesis  of  “continental  disruption”  or  the  “displace¬ 
ment  hypothesis,  ”  brought  forward  independently  by  F.  B.  Taylor1 
and  A.  Wegener,2  that  the  present  continents  have  owed  their  posi- 


1  Taylor  (1910). 


2Wegener  (1912). 


1 


2  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

tions  in  great  part  to  the  breaking-up  of  much  larger  land-masses  in 
the  Cretaceo-Tertiary  through  the  “drifting  apart”  of  the  crustal 
fragments,  has  on  the  contrary  helped  to  bring  numerous  other 
irreconcilable  facts  into  harmony  and  would  almost  seem  to  have 
provided  us  with  the  key  to  the  riddle  of  the  structure  of  the  earth 
and  more  particularly  of  the  history  of  “Gondwanaland.  ” 

In  1916, 3  though  in  ignorance  of  the  details  of  Wegener’s  doctrine, 
the  writer  put  forward  an  hypothesis  somewhat  different  from  those 
of  Taylor  and  Wegener,  the  outcome  of  the  study  mainly  of  the 
glacial  deposits  of  the  Karroo  system,  supplemented  by  a  personal 
acquaintance  with  their  Australian  equivalents.  Later  developments 
having  seemingly  rendered  these  ideas  more  and  more  worthy  of 
serious  consideration,  it  became  one  of  his  aims  to  visit  South  Amer¬ 
ica  in  the  hopes  of  being  able,  while  gathering  information  about  the 
Gondwana  deposits  of  that  continent,  to  discover  any  evidence 
favorable  or  adverse  to  the  “displacement  hypothesis.  ” 

Following  the  sympathetic  representation  by  Dr.  Fred.  E. 
Wright,  of  the  Geophysical  Laboratory  of  the  Carnegie  Institution 
of  Washington,  and  Dr.  Reginald  A.  Daly,  of  Harvard  University, 
the  president  (Dr.  John  C.  Merriam)  and  trustees  of  the  Carnegie 
Institution  of  Washington,  appreciative  of  the  scientific  importance 
of  such  a  mission,  most  generously  offered  a  grant  in  aid,  and,  making 
use  of  my  six  months  of  leave  from  official  duties,  fortunately  then 
available,  I  was  enabled  to  cross  the  Atlantic  and  spend  five  months 
in  Brazil,  Uruguay,  and  Argentina.  To  the  Carnegie  Institution  of 
Washington,  in  thus  promoting  research  in  the  Southern  Hemisphere, 
I  am  accordingly  under  the  deepest  of  obligations,  while  I  have  fur¬ 
ther  to  thank  them  also  for  their  generosity  in  publishing  the  results 
of  these  investigations,  rather  unfortunately  delayed  by  reason  of 
pressing  official  and  other  duties. 

Taking  into  account  the  enormous  size  of  the  region  traversed 
and  the  time  necessarily  consumed  in  traveling,  the  opportunities 
for  original  investigation  were  naturally  limited,  and  it  was  often 
with  keen  regret  that  a  particular  line  of  research  had  to  be  dropped 
just  as  it  was  disclosing  results  of  consequence.  Nevertheless,  the 
knowledge  so  acquired  has  permitted  the  copious  scattered  literature 
to  be  read  with  a  certain  amount  of  discrimination  and  has  enabled  a 
closer  comparison  of  the  Gondwana  system  of  South  America  to  be 
made  with  that  of  South  Africa  than  has  hitherto  been  possible. 
Papers  in  the  English  language  on  the  geology  of  any  part  of  South 
America  are  relatively  few,  while  those  in  Spanish  or  Portuguese 
dealing  comprehensively  with  any  one  of  its  republics  are  equally 
rare.  Consequently,  instead  of  limiting  this  account  to  the  points 
investigated  personally,  the  opportunity  has  been  taken,  although  at 

*  Du  Toit  (1916). 


INTRODUCTION 


3 


the  risk  of  undue  length,  of  reviewing  in  addition  the  geology  of 
South  America  in  so  far  as  it  may  have  a  bearing  on  the  problem  of 
Gondwanaland  and  of  a  former  connection  between  Africa  and  the 
New  World.  The  extraordinarily  divergent  conclusions  reached  on 
many  vital  questions  by  various  eminent  South  American  geologists 
is  eloquent  proof  indeed  as  to  the  need  of  such  a  summary  for 
the  benefit  of  English-speaking  persons.  Furthermore,  the  notable 
advances  made  in  recent  years  have  rather  impaired  the  value  of  that 
monumental  work  by  Suess,  The  Face  of  the  Earth,  which  even  the 
French  edition  with  its  new  maps  and  copious  references  to  recent 
literature  just  fails  to  restore. 

In  this,  the  first  comprehensive  summary  of  the  geology  of  the 
eastern  part  of  South  America,  considerable  liberty  has  been  taken 
in  the  interpretation  of  the  accounts  of  areas  which  naturally  could 
not  be  visited,  and  doubtless  there  will  be  found  not  a  few  statements 
or  conclusions  to  which  the  local  geologists  can  and  will  take  excep¬ 
tion.  It  is  nevertheless  hoped  that  such  differences  in  the  presenta¬ 
tion  and  interpretation  may  not  be  of  too  violent  a  character;  for 
such  the  insufficiency  of  the  data,  even  for  the  better  known  parts 
of  this  enormous  territory,  must  in  part  be  held  responsible.  Con¬ 
siderable  difficulty  was  experienced  in  the  preparation  of  the  accom¬ 
panying  geological  map ;  drastic  alterations  are  required  to  Branner’s 
map  of  Brazil,4  while  that  by  Leme,5  though  more  up  to  date,  is  on  a 
smaller  scale  and  not  sufficiently  detailed;  Walther’s  map  of  Uru¬ 
guay  6  is  valuable,  but  there  is  no  general  map  of  Argentina,  while 
much  of  Paraguay,  Bolivia,  and  the  adjacent  part  of  Brazil  are 
geologically  unexplored. 

I  found  my  South  American  confreres  keenly  interested  in  the 
problems  herein  discussed,  though  the  size  of  their  countries,  the 
smallness  of  the  staffs,  the  pressure  of  economic  work,  and  the  lack  of 
coordinated  effort  between  the  geological  surveys  of  the  various 
republics  and  states  have  hindered  the  carrying  out  of  any  compre¬ 
hensive  scheme  of  work  thereon.  Furthermore,  no  one  had  any 
first-hand  acquaintance  with  any  of  the  other  countries  possessing 
Gondwana  beds.  I  have  reason  to  believe  that  interest  in  these 
problems  has  been  appreciably  stimulated  as  the  consequence  of 
this  visit.  While  immediate  results  therefrom  could  hardly  be 
expected,  attention  might  be  drawn  to  a  paper  by  Professor 
Walther7  on  the  Borings  for  Coal  in  Cerro  Largo,  Uruguay,  and 
one  by  Senor  E.  T.  Arocena8  on  the  Glacials  in  the  Department  of 
Durazno  as  the  outcome  of  certain  observations  made  by  the  writer 
in  that  republic. 

In  order  to  aid  comparisons  with  the  African  continent,  a  brief 

4Branner  (1919).  6  Walther  (1919).  8Arocena  (1926). 

6 Leme  (1924).  7  Walther  (1924). 


4  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

account  is  given  of  the  geological  features  of  its  western  side,  the 
literature  thereon  being  rather  scattered,  with  much  uncertainty 
pertaining  to  the  territories  from  Angola  northward,  while  a  sum¬ 
mary  of  the  geology  of  the  important  Falkland  Islands  has  also  been 
introduced  for  reasons  that  will  appear  in  the  sequel. 

The  schematic  representation  embodied  in  Figure  7  will  assuredly 
be  subjected  to  active  and  probably  to  hostile  criticism  on  the  score 
of  the  fantastic  and  apparently  improbable  character  of  the  dis¬ 
placement  theory,  but  a  close  and  impartial  study  thereof  is  invited, 
so  that  the  numerous  congruences  and  '‘coincidences”  in  the  stra¬ 
tigraphy,  structure,  etc.,  of  the  two  great  land-masses  now  parted 
by  the  South  Atlantic  may  be  duly  scrutinized  and  pondered  over, 
the  weaknesses  of  the  arguments  advanced  duly  pointed  out,  and 
more  reasonable  alternatives  suggested  in  explanation  of  the  facts  or 
their  interpretation. 


Leaving  Cape  Town  on  June  12, 1923,  Rio  de  Janeiro  was  reached 
a  fortnight  later,  where  the  director  of  the  Geological  Service, 
Dr.  Euzebio  Paulo  de  Oliveira,  with  the  permission  of  the  Brazilian 
government,  kindly  detailed  Dr.  L.  F.  Moraes  Rego  to  act  as  my 
guide  and  instructor,  under  whose  able  direction  a  tour  was  made  of 
nearly  six  weeks’  duration,  the  department  obligingly  providing 
rail  transport.  The  program  embraced  a  short  visit  to  Ouro  Preto, 
Bello  Horizonte,  and  Diamantina  to  inspect  the  ancient  formations 
of  Minas  and  the  Boa  Vista  Diamond  “pipe.”  The  journey  from 
Sao  Paulo  to  Ityrapina  and  Bauru  provided  sections  of  the  Triassic 
“traps”  and  the  Cretaceous  of  the  interior,  while  a  trip  through 
Ponta  Grossa,  Iraty,  Roxo  Roiz,  Marechal  Mallet,  Rio  Claro,  Porto 
Uniao,  and  Rio  Negro  to  Curityba  enabled  the  Devonian  as  well  as 
the  full  succession  of  the.Gondwana  system  to  be  studied.  Taking 
the  steamer  from  Paranagua  to  Porto  Alegre,  Taquara,  Cachoeira, 
Ferreira,  Santa  Maria,  and  Sant’  Anna  were  visited,  enabling  good 
sections  of  the  Triassic  sediments  and  volcanics  to  be  inspected. 

In  Uruguay  the  director  of  the  Section  of  Geology  and  Water 
Boring,  Senor  E.  Terra  Arocena,  generously  placed  his  records  at  my 
disposal,  while  Dr.  Karl  Walther,  professor  of  Geology  at  the  Insti¬ 
tute  of  Agronomy,  Montevideo,  kindly  supplied  me  with  valuable 
information.  Fraile  Muerto  provided  confirmation  of  the  existence 
of  Carboniferous  glacial  beds,  originally  reported  therefrom  by 
Guillemain,  while  Melo,  Paso  del  Cerro,  Santa  Rosa,  and  Sauce  were 
also  visited. 

In  Buenos  Aires,  through  the  courtesy  of  the  Minister  for  Mines, 
the  director  of  the  Geological  Survey,  Dr.  J.  M.  Sobral,  whole¬ 
heartedly  detailed  several  of  his  staff  to  accompany  me  in  turn  on  a 


INTRODUCTION 


5 


tour  of  nearly  two  months,  namely,  Dr.  Franco  Pastore,  Dr.  Augusto 
Tapia,  and  Dr.  Juan  J.  Nagera,  the  government  defraying  the  cost 
of  rail  transport.  The  route  lay  through  Villa  Dolores,  Bajo  de  Velis, 
Cordoba,  La  Cumbre,  Capilla  del  Monte,  Marayes,  San  Juan,  Men¬ 
doza,  Cacheuta,  Uspallata,  Barreal,  and  across  the  Andes  to  Val¬ 
paraiso  in  Chile  and  back  to  Buenos  Aires ;  this  enabled  the  various 
horizons  in  the  Gondwana  system  to  be  inspected.  Trips  were  made 
to  Olavarria,  Sierra  de  la  Ventana,  and  La  Plata  to  study  the  equiva¬ 
lents  of  the  “Cape  Fold  ranges.  ” 

The  return  journey  was  made  by  Montevideo,  Santos,  Sao  Paulo, 
Rio  de  Janeiro,  and  Pernambuco.  Through  the  kindness  of  Dr. 
Miguel  A.  de  Lisboa,  director  of  Irrigation,  a  rapid  journey  was 
made  by  rail  to  Campina  Grande  and  thence  to  the  irrigation  dams 
under  construction  at  Gargaleira  and  Parelhas  in  Rio  Grande  do 
Norte,  every  facility  being  placed  at  my  disposal  by  the  Brazilian 
government  through  the  agency  of  Doctor  Netto.  The  voyage  there¬ 
after  was  made  via|Madeira|  arriving  at  Cape  Town  on  December 
io,  1923. 

Among  the  numerous  other  persons  to  whom  I  have  been  particu¬ 
larly  indebted  are  Drs.  T.  H.  Lee,  Paulino  F.  de  Carvalho,  and 
Axel  Lofgren,  of  the  Brazilian  Geological  Service,  Dr.  Joviano  A. 
Pacheco,  head  of  the  Geographical  and  Geological  Commission 
of  the  State  of  Sao  Paulo,  Drs.  Pablo  Groeber,  Roberto  Beder,  Juan 
Rassmuss,  Anselmo  Windhausen,  Ricardo  Wichmann,  and  Hausen, 
of  the  Geological  Survey  of  Argentina,  Dr.  Juan  Keidel,  formerly 
director  of  that  survey,  Dr.  H.  Schiller,  of  the  Museum  of  La  Plata, 
Dr.  C.  Hosseus,  of  the  University  of  Cordoba,  and  Mr.  H.  J.  Hawley, 
geologist  to  the  Standard  Oil  Company.  To  my  former  South  African 
friends,  Mr.  Bernard  W.  Ritso,  M.I.C.E.,  late  director  of  the  Section 
of  Water  Boring  in  Uruguay,  Mr.  David  Draper,  F.G.S.,  manager  of 
the  Boa  Vista  Diamond  Mine,  to  Mr.  F.  W.  Scott,  M.I.C.E.,  engi- 
neer-in-charge  at  Gargaleira,  and  Mr.  B.  H.  Heatlie,  of  Buenos  Aires, 
I  am  under  great  obligations.  Furthermore,  to  Mr.  L.  S.  Goldsmith, 
of  the  Geological  Survey,  Pretoria,  is  due  the  lettering  on  the  Geo¬ 
logical  map. 

My  thanks  are  due  to  Dr.  R.  S.  Bassler,  of  the  United  States 
National  Museum,  Washington,  for  his  opinion  on  the  invertebrate 
fossils  collected  in  Brazil  and  Argentina,  whilst,  finally,  I  am  exces¬ 
sively  indebted  to  my  friend  Dr.  F.  R.  Cowper  Reed,  of  the  Sedgwick 
Museum,  Cambridge,  England,  for  his  labors  on  these  collections, 
the  results  of  which  are  embodied  in  the  valuable  Appendix  to  this 
report.  His  noteworthy  discovery  of  the  Triassic  affinities  of  the 
Estrada  Nova  mollusca  was,  however,  only  made  while  this  work  was 
in  the  press,  and  it  has  been  found  impossible  at  this  late  stage  to  do 
full  justice  thereto  and  avoid  some  minor  inconsistencies  in  the  text. 


CHAPTER  II 

GEOLOGICAL  FRAMEWORK  OF  THE  SOUTH  ATLANTIC 
SECTION  A.  THE  WESTERN  SIDE  OF  AFRICA 

For  convenience  we  may  divide  this  region  into  two  portions: 

(i)  that  from  the  extreme  south  of  the  Cape  up  to  the  Cunene 
River,  of  which  the  geology  is  now  firmly  established,  while  forma¬ 
tions  younger  than  the  Triassic  are  scarcely  represented,  and  (2) 
that  from  the  Cunene  River  northward,  for  which  reliable  data  are 
often  ’wanting,  while  the  coastal  strip,  just  as  in  the  opposed  section 
of  Brazil,  is  made  up  largely  of  marine  Cretaceous  and  Tertiary 
deposits. 

(1)  The  southern  section ,9  embracing  part  of  the  Cape  Province 
and  Territory  of  Southwest  Africa  (formerly  German  Southwest 
Africa),  displays  a  great  stretch  of  Archaean  rocks  from  the  Cunene 
River  southward  to  Van  Rhynsdorp,  having  a  northeasterly  strike 
in  the  Swakopmund-Windhoek  region.  Younger,  though  probably 
of  Cambrian  or  pre-Cambrian  age,  is  the  Nama  system,  with  a  basal 
series  of  conglomerates  and  quartzites  reposing  unconformably  on  the 
crystallines,  followed  by  limestones,  dolomites,  and  shales,  and  these 
by  red  sandstones,  red  and  green  shales,  and  gray  and  red  quartz¬ 
ites.  Though  nearly  flat -lying  inland,  e.g.,  at  Kuibis,  this  formation, 
on  approaching  the  coast,  suddenly  displays  folding  along  axes 
following  the  ocean  margin  closely,  from  Liideritz  to  the  mouth  of  the 
Olifants  River  continued  with  a  south-southeasterly  to  southeasterly 
strike  through  the  Western  Province  of  the  Cape.  These  crumplings  , 
which  were  accompanied  by  intrusions  of  granite,  are  of  pre- 
Devonian  age,  but  in  the  south  a  renewal  of  movement  took  place 
along  them  in  late  Carboniferous  times. 

Upon  a  worn-down  surface  of  these  rocks  was  deposited  the 
triply-divided  Cape  system  some  3,300  meters  in  thickness,  widely 
distributed  over  the  southern  third  of  the  Cape  Province.  The 
Lower  Devonian  Table  Mountain  sandstone  at  the  base,  some  1,600 
meters  thick,  is  composed  of  unfossiliferous,  whitish,  hard  sandstones 
and  grits  characterized  by  tiny  pebbles  of  white  or  gray  vein-quartz 
and  sometimes  of  red  jasper,  while  current-bedding  is  conspicuous. 
An  important  feature  is  the  occurrence  of  a  fine  glacial  horizon  some 
700  meters  above  the  base,  the  material  having  been  derived  from 
some  locality  lying  out  in  the  present  Atlantic. 

Then  follows  the  Bokkeveld  series  of  shales  and  sandstones,  with 
its  Lower-Middle  Devonian  “Austral”  invertebrate  fauna  and  above 

•  For  fuller  details  see  Du  Toit  (1926). 

6 


GEOLOGICAL  FRAMEWORK  OF  THE  SOUTH  ATLANTIC 


7 


it  the  Witteberg  series  (upper  Devonian-lower  Carboniferous)  of 
white  quartzites,  with  some  poorly  preserved  plant  remains.  The 
source  of  all  these  Palaeozoic  sediments  lay  in  the  north  and  north¬ 
west.  In  the  neighborhood  of  the  Olifants  River  mouth  these  beds 
are  lying  nearly  flat,  but  on  proceeding  southward  folding  is  dis¬ 
covered  that  follows  the  much  older  south-southeasterly  directed 
crumplings,  while  near  Ceres  a  second  series  of  foldings  appears  with 
a  general  west-east  trend  continuing  to  the  Indian  Ocean ;  the  moun¬ 
tainous  belt  thus  formed  is  known  as  the  “Cape  Fold  ranges.  ” 

South  of  latitude  33 °  the  Witteberg  passes  up  without  a  break 
into  the  upper  Carboniferous  glacials  of  the  Dwyka  series,  which 
constitutes  the  lowest  member  of  the  Karroo  system,  and  which,  par¬ 
taking  in  the  above-mentioned  foldings,  possesses  a  thickness  of 
over  400  meters  and  seems  to  have  been  largely  deposited  in  standing 
water  by  ice-sheets  originating  in  the  north.  North  of  the  thirty- 
third  parallel  the  tillite  is  found  undisturbed,  but  transgresses  across 
the  Cape  system  and  older  groups  to  rest  upon  the  Archaean,  while 
the  floor  beneath  it  becomes  uneven  and  in  good  exposures  reveals 
typically  striated  roches  moutonnZes .  The  horizontal  tillite  is  a  true 
ground-moraine  and  can  be  traced  through  Calvinia  and  Bushman- 
land  to  appear  again  beyond  the  Orange  River,  whence  it  con¬ 
tinues  northward  in  Southwest  Africa  up  the  Fish  River  Valley  to 
Mariental,  but  has  not  yet  been  recognized  north  of  that  point. 

The  succeeding  beds,  sometimes  sharply  defined,  but  often 
carrying  small  erratics,  compose  the  upper  Dwyka  Shales  and  pass 
up  into  a  zone  of  white-weathering  carbonaceous  and  pyritic  shales 
with  occasional  casts  of  the  small  reptile  Mesosaurus ,  and,  together 
•with  some  dolomite  and  chert,  constitute  the  horizon  of  the  “White 
band,  ”  the  thickness  of  these  post-glacial  beds  being  from  150  to  160 
meters,  approximately.  These  strata  are  recognizable  from  Robert¬ 
son  in  the  south  to  Mariental  in  the  north,  but  fragments  of  Meso¬ 
saurus  have  been  obtained  from  the  Kaokoveld  in  latitude  20°  45'. 
All  this  is  instructive  when  comparison  is  being  made  with  the  almost 
identical  Iraty  shales  of  Brazil  with  this  similar  zone  fossil.  No  coals 
occur  in  the  Dwyka  shales,  though  the  Brazilian  seams  appear  to  be 
on  the  corresponding  horizon. 

The  White  band  passes  up  in  the  southern  Karroo  into  the  Ecca 
series,  a  thick  group  of  greenish,  bluish,  and  sometimes  purplish 
shales  and  flagstones  with  calcareous  nodules  and  dark-green  or  gray 
sandstones  that  have  yielded  silicified  wood  and  the  Gangamopteris 
flora,  but  to  the  northeast  and  to  the  north  entirely  different  facies 
in  the  series  have  been  developed.  For  instance,  in  Calvinia  the 
group  is  composed  almost  entirely  of  dark-bluish,  soft  shales,  while 
in  the  southern  Kalahari  and  to  the  northeast  of  Keetmanshoop  the 
strata  are  now  largely  red,  the  formation  consisting  of  deep-red  and 


8  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

green-blue  shales  with  brown-weathering  calcareous  bands  and  soft 
yellowish  and  reddish  sandstones,  a  facies  closely  comparable  with 
the  second  and  third  stages  of  the  Paganzo  system  of  western  Argen¬ 
tina  and  also  somewhat  like  the  Estrada  Nova  group  in  Uruguay.  In 
the  Transvaal,  on  the  other  hand,  the  overlap  of  the  several  sub¬ 
divisions  of  the  Dwyka  and  Ecca  has  taken  place  on  to  the  thin 
glacial  conglomerate  or  else  on  to  the  pre-Karroo  rocks,  while  a 
fluviatile  and  thinner  phase  of  the  Ecca  has  led  to  the  production  of 
the  Transvaal  and  Natal  “Coal  Measures,”  a  group  of  pale  grits, 
conglomerates,  arkoses,  and  sandstones,  with  dark  micaceous  shales 
and  seams  of  coal  often  from  2  to  8  meters  in  thickness.  The  flora  is 
the  ‘  ‘  southern  ’  ’  one,  allied  to  that  of  the  Karharbari  of  India  or  the 
Greta  stage  of  New  South  Wales,  but  with  some  “northern”  ele¬ 
ments,  a  Lower  Permian  age  being  indicated. 

The  succeeding  Beaufort  series,  well  over  1,000  meters  thick,  in 
the  southwest,  is  made  of  greenish  mudstones  and  shales,  often  varie¬ 
gated  and  carrying  calcareous  concretions,  together  with  yellowish 
felspathic  sandstones,  the  beds  being  conspicuously  red  and  maroon 
near  the  top.  Small  local  depositional  unconformities  are  common 
and  the  beds  are  decidedly  of  the  “interior  basin”  type.  A  fairly 
abundant  reptilian  and  amphibian  fauna  and  a  scanty  flora  allied  to 
that  of  the  Damuda  of  India  and  Newcastle  of  New  South  Wales, 
collectively  indicate  an  age  covering  the  upper  Permian  and  lower 
Triassic.  This  formation  is  unrepresented  to  the  northeast  in  the 
central  Transvaal  and  to  the  northwest  in  Southwest  Africa. 

The  Stormberg  series  embraces  the  plant-  and  coal-bearing 
Molteno  group  of  grits,  sandstones,  and  gray  and  blue  shales,  the 
striking  deeply-colored  group  of  the  Red  beds  and  massive  contrasting 
cream  or  pink  Cave  sandstone  and  finally  the  Drakensberg  volcanics, 
the  whole  assemblage  representing  the  upper  Triassic,  Rhaetic,  and 
just  possibly  the  Liassic.  While  conformable  to  the  Beaufort  in  the 
south,  this  series  transgresses  across  the  Ecca  or  even  the  pre-Karroo 
rocks  in  the  Transvaal,  Southwest  Africa,  and  Southern  Rhodesia,  so 
that  the  Red  beds,  Cave  sandstone  (and  its  equivalents,  the  Bushveld 
and  Forest  sandstone)  and  basalts  come  to  cover  wide  tracts  without 
the  intervention  of  the  Molteno  or  older  groups,  a  feature  paralleling 
the  conditions  to  be  found  in  South  America  in  the  case  of  the  Trias- 
Rhaetic  beds.  The  series  is  well  developed  in  the  Kaokoveld,  where 
it  makes  the  coast-line  for  quite  a  considerable  distance. 

The  Molteno  flora  with  its  characteristic  genus  Thimifeldia,  is 
extremely  like  that  of  the  “Rhaetic”  of  western  Argentina,  though, 
the  vertebrates  ( saurischia  and  pseudosuchia )  of  the  Red  beds  and 
Cave  sandstone  confer  an  age  not  younger  than  Rhaetic  for  these 
succeeding  sediments.  The  Basaltic  lavas  cover  broad  areas  and 
must  have  had  a  much  wider  extension  formerly;  they  exceed  400 


GEOLOGICAL  FRAMEWORK  OF  THE  SOUTH  ATLANTIC 


9 


meters  in  depth  in  each  of  the  main  areas,  the  maximum  thickness 
known  being  about  1,300  meters.  Dolerite  sills  and  dikes,  closely 
related  to  the  lavas,  are  most  abundantly  represented  in  the  Karroo 
beds  from  Sutherland  and  Beaufort  West  in  the  south  right  up  into 
Southwest  Africa,  a  feature  closely  paralleled  in  the  Parana  Basin 
in  Brazil. 

Cretaceous  (Neocomian-Wealden)  beds  and  Tertiaries  (Eocene- 
Pliocene)  are  represented  within  the  Coastal  Belt  of  the  south  of  the 
Cape,  but  no  undoubted  marine  Cretaceous  is  known  along  the 
Atlantic  shore  south  of  the  Cunene  River  nor  directly  opposite  in 
South  America. 

(2)  In  the  less  known  northern  area  Cretaceous  and  Tertiary 
beds,  largely  marine  in  origin,  fringe  the  coast  from  Lobito  Bay  in 
Angola  up  to  French  Congo,  widening  out  where  traversed  by  the 
Cuanza  and  Congo  Rivers,  while  in  the  former  region  the  strata  are 
actually  flexed  along  axes  concave  towards  the  west  and  are  also 
faulted.  Dipping  beneath  them  in  places  are  the  Dombe  sandstones 
and  in  the  Congo  section  the  “Gres  sublittoraux ”  of  Fourmarier,10 
which  have  been  regarded  by  Choffat  as  Lower  Cretaceous,  but  by 
others  as  of  Triassic  age.  The  Albian  of  Benguella  is  of  importance 
because  of  the  presence  of  certain  forms  common  or  allied  to  the 
Sergipe  Cretaceous  of  Brazil,  as  pointed  out  by  Kossmatt,  Newton, 
Gregory,  and  others. 

The  plateau  to  the  east  of  Benguella,  formed  of  crystallines  and 
belts  of  ancient  sediments,  is  crowned  with  the  Bihe  sandstone,11 
which  is  probably  merely  the  fringe  of  the  Lubilache  series  that 
covers  such  an  enormous  area  within  the  Congo  Basin,  with  its 
western  boundary  passing  through  Leopoldville  northward  to  the 
borders  of  the  Cameroons,  a  distance  of  over  1,500  km.  This  forma¬ 
tion,  several  hundred  meters  thick,  is  composed' of  horizontal  friable 
white,  yellowish,  or  reddish  sandstones,  often  displaying  curious  sur¬ 
face  silicification.  On  the  eastern  side  of  this  immense  basin  they 
repose  upon,  but  quite  possibly  to  some  extent  pass  laterally  into, 
the  shales  and  sandstones  of  the  Lualaba  series.  The  age  of  these 
groups,  as  determined  from  some  fish  and  crustacean  remains,  is 
Triassic  or  Rhaetic  and  they  correspond  therefore  with  the  Stormberg 
series  farther  to  the  south.  In  the  west  the  Lubilache  generally  rests 
with  unconformity  upon  the  slightly  folded  strata  ascribed  to  the 
Kundulungu  series,  a  group  of  deep-red  shales  and  micaceous  flag¬ 
stones  alternating  with  gray  or  light-red  sandstones  and  becoming 
more  felspathic  and  coarser  toward  the  summit.  There  are  serious 
differences  of  opinion  as  to  the  age  of  this  formation  as  seen  in  the 
Lower  Congo  or  in  French  Congo,  which  can  not  be  settled,  owing 

10 Fourmarier  (1924).  11  Gregory  (1916),  p.  523. 


10  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

to  the  absence  of  fossils,  but  a  Permian  or  Carboniferous  age  is  just 
possible,  and  if  so,  the  group  would  correspond  to  the  lithologically 
similar  Estancia  beds  of  Bahia  and  Sergipe. 

The  Kundulungu  in  turn  rests  disconformably  upon  the  system 
“  Schisto-calcaire,  ”  a  group  unconformable  to  the  pre-Cambrian 
complex,  having  a  basal  conglomerate  stated  by  Delhaye  and  Sluys 12 
to  be  largely  of  glacial  origin,  followed  by  over  1,000  meters  of  lime¬ 
stones  and  dolomites,  occasionally  oolitic,  but  as  yet  not  proved 
fossiliferous.  They  either  correspond  with  the  Otavi  dolomite 
(Nama)  of  Southwest  Africa — probably  Proterozoic — or  are  of  early 
Palaeozoic  age  and  hence  possibly  comparable  with  the  Bambuhy 
series  of  eastern  Brazil.  These  beds  display  strong  foldings  directed 
nearly  north-northwest,  crossed  by  a  set  at  right  angles  thereto, 
along  the  latter  of  which  a  renewal  of  movement  occurred  probably 
in  the  Permian  as  well  as  in  still  later  times. 

From  Cameroons  the  coast  of  Africa  turns  abruptly  westward 
and  a  region13  is  reached  displaying  many  points  of  similarity  with 
the  Pernambuco-Maranhao  territory  of  Brazil.  Along  the  low-lying 
coast,  extending  from  Cameroons  to  Accra,  with  a  tongue  reaching 
into  northern  Nigeria,  is  a  curving  belt  of  marine  Tertiaries,  in  which 
zones  so  far  back  as  the  Eocene  are  to  be  found,  resting  upon  either 
Cretaceous  or  ancient  formations  and  passing  beneath  younger 
deposits.  Bituminous  shales  and  lignites  are  known  from  the  earlier 
tertiaries  in  several  areas  and  can  be  compared  with  the  Eocene 
bituminous  shales  with  fish  remains  in  Alagoas  and  perhaps  Maran- 
hao.  Much  of  the  western  part  of  Africa  was  inundated  by  the 
Cretaceous  ocean,  and  wide  tracts  of  the  hinterland  are  covered  by 
marine  beds  belonging  to  various  stages  of  that  epoch,  just  as  is  so 
marked  a  feature  of  Ceara,  Piauhy,  and  Maranhao.  On  both  sides  of 
the  Atlantic  these  strata  have  locally  been  affected  by  post-Creta¬ 
ceous  movements. 

Among  the  older  formations  might  be  mentioned  the  Buem  series 
on  the  eastern  side  of  the  Volta  River  in  Togoland,  composed  of  con¬ 
glomerates,  arkoses,  quartzites,  and  shales,  of  which  certain  con¬ 
glomerates  have  been  regarded  as  of  morainic  origin  by  Koert  and 
hence  of  Permo-Carboniferous  age ;  Lemoine  classes  them,  however, 
in  the  Devonian.  Conspicuous  is  the  tectonic  line  of  the  Atacora 
Range  south  of  the  Niger  in  Dahomey — the  “Saharides”  of  Suess — 
in  which  a  belt  of  folded  quartzites  and  schists,  flanked  by  crystal¬ 
lines,  ascribed  to  the  Silurian,  but  probably  older,  strikes  north- 
northeastward  from  the  Gold  Coast  and  thence  at  intervals  into  the 
Sahara,  where  the  folds  now  trend  more  nearly  northward ;  associated 
is  the  Tarkwa  series  in  Gold  Coast  Colony  with  northeastward  strike 
and  certainly  pre-Palasozoic. 

12  Delhaye  and  Sluys  (1921). 


13 Lemoine  (1913). 


GEOLOGICAL  FRAMEWORK  OF  THE  SOUTH  ATLANTIC 


11 


This  brings  us  to  the  consideration  of  the  undoubted  Palasozoic 
rocks  of  western  Africa  and  central  Sahara.  On  the  borders  of  Sierra 
Leone  and  French  Guinea,  resting  unconformably  on  schistose  rocks, 
is  an  undulating  sandstone  formation  carrying  Silurian  (Wenlock) 
graptolites,14  apparently  the  beginning  of  the  huge  area  of  horizontal 
sandstones  on  the  upper  Niger  building  up  the  plateau  of  Homboi 
(“Bandiagara  sandstone”)  and  south  of  the  great  bend  of  the  Niger, 
but  which  have  not  as  yet  been  proved  fossiliferous.  To  the  north¬ 
east  the  Silurian  of  Tuareg  and  Air  is  folded  and  overlain  by  gently 
dipping  Lower  Devonian  possessing  a  fauna  including  in  addition  to 
European  forms,  not  only  some  from  North  America,  but  certain 
from  the  Bokkeveld  as  determined  by  Haug.15  Future  work  will 
doubtless  add  largely  to  the  known  area  of  Palaeozoics  in  this  part  of 
Africa.  Of  great  importance  too  is  the  occurrence  of  the  Middle 
Devonian  in  a  small  down-faulted  block  at  Accra  on  the  Gold  Coast, 
with  a  “Hamilton”  fauna,16  while  slates,  provisionally  placed  in  the 
Lower  Carboniferous  because  of  certain  poorly  preserved  mollusca — 
but  possibly  Devonian — are  known  at  Sekondi  to  the  west  of  Accra. 

Undoubted  pre-Mesozoic  marine  beds  have  not  yet  been  found  to 
the  southeast  in  Cameroons,  and  the  presence  of  this  wide,  though 
interrupted  belt  extending  from  Sierra  Leone  into  the  Sahara,  in 
which  marine  Palaeozoic  beds  have  been  developed,  is  of  immense 
importance,  inasmuch  as  it  shows  correspondence  with  the  broad, 
shallow  syncline  of  marine  Silurian,  Devonian,  and  Carboniferous 
strata  within  the  lower  Amazon  Valley  in  which  similar  faunal  ele¬ 
ments  are  actually  present. 

SECTION  B.  THE  FALKLAND  ISLANDS 

These  remarkable  islands,  of  which  a  brief  geological  sketch  can 
not  be  omitted,  constitute  a  most  striking  link  between  South  Africa 
and  South  America,  despite  the  fact  that  they  are  situated  only  a  few 
degrees  from  Patagonia  and  well  down  below  the  fiftieth  parallel. 
Our  knowledge  concerning  them  has  been  enormously  extended 
through  the  work  of  Andersson 17  and  after  him  Halle,18  with  H.  A. 
Baker 19  just  recently,  while  the  Devonian  molluscan  fauna  has  been 
discussed  by  J.  M.  Clarke20  and  the  Gondwana  flora  described  by 
Halle,  Seward  and  Walton.21 

The  dominant  Devono-Triassic  succession  has  been  affected  by 
two  main  tectonic  structures.  The  more  important  of  these,  marked 
by  strong  folding  and  some  faulting,  traverses  the  northern  part  of 
East  Island,  trending  west  to  west-northwest  and  curving  more  to  the 

14Dixey  (1925),  p.  213;  Lecointre  and  Lemoine  (1925). 

16  Haug  (1905). 

16Kitson  and  Morley  Davies  (1925).  19  Baker  (1923). 

17  Andersson  (1907).  20  Clarke  (1913)*  P-  55»  P*  32^. 

18  Halle  (1912).  21  Seward  and  Walton  (1923). 


12  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

northwest  through  the  northern  side  of  West  Island,  with  some 
parallel  subsidiary  flexuring  in  the  center  of  that  land;  the  other 
structure  crosses  nearly  at  right  angles,  striking  south  west  ward  along 
both  shores  of  Falkland  Sound.  In  the  southern  side  of  East  Island 
and  the  southwestern  side  of  West  Island  the  beds,  on  the  contrary, 
undulate  slightly  or  are  flat. 

The  lower  Devonian  sandstones  are  restricted  to  the  southwestern 
side  of  West  Island,  resting  unconformably  upon  crystallines  at 
Cape  Meredith  and  having  a  thickness  of  many  hundred  meters. 
The  series  is  extraordinarily  like  the  Table  Mountain  sandstones  of 
the  Cape  Province,  consisting  of  a  group  of  unfossiliferous,  pale, 
false-bedded  sandstones  and  quartzitic  sandstones  with  some  red 
micaceous  shales  at  the  very  base,  while  small  pebbles  of  white  vein- 
quartz  are  common,  making  in  places  conglomerates.  It  passes 
beneath  a  group  of  slaty  rocks,  shales,  flagstones,  and  sandstones  that 
has  yielded  a  typical  “austral”  Devonian  fauna,  overlain  by  similar 
beds  with  lepidodendroid  plant  remains  and  thus  like  the  Bokkeveld 
series  of  the  Cape.  Of  the  mollusca,  some  20  species  are  common 
to  the  latter  and  some  2  5  to  the  equivalent  Devonian  of  South  Amer¬ 
ica,  including  in  each  case  several  trilobites,  besides  other  closely 
allied  forms.  This  group  is  succeeded  by  quartzites  and  quartzitic 
sandstones  and  interlaminated  shales  that  correspond  with  the 
Witteberg  series.  Baker  has  pointed  out  these  surprising  resem¬ 
blances  with  the  Cape  system,  not  only  lithologically,  but  in  regard 
to  thickness  as  well,  so  far  as  such  can  be  made  out  in  the  folded 
ranges  of  East  Island. 

The  Gondwana  beds  are  referred  to  as  the  Lafonian  system, 
having  a  thickness  of  possibly  over  3,000  meters  and  occupy  the 
southern  half  of  East  Island,  but  are  brought  down  by  folding  in  a 
few  localities  in  West  Island.  At  the  base  are  glacial  boulder-beds 
about  650  meters  thick,  identical  in  their  characters  with  those  of  the 
,  Dwyka  tillite,  usually  folded  and  cleaved,  with  striated  erratics  often 
traversed  by  regular  jointing;  underneath  them  Baker  has  discovered 
some  quartzite  surfaces  with  striations  running  from  north  to  south, 
presumably  glaciated  floors.  Some  passage  beds  with  small  inclu¬ 
sions  lead  up  into  the  Lafonian  sandstone,  and  this  in  turn  into 
“banded  siltstones,  ”  apparently  seasonally  banded  “varve”  rocks 
representing  glacial  material  deposited  in  fresh  water. 

Next  comes  a  huge  group  of  alternating  brown,  yellow,  gray,  and 
green  mudstones,  shales  and  similarly  colored  sandstones  and  hard 
greenish  sandstones  in  which  occur  members  of  the  Glossopteris 
flora.  The  form  identified  by  Halle  as  Gangamopteris  is  regarded  by 
Seward  and  Walton22  as  more  probably  a  Glossopteris ,  with  which 
occur  G.  browniana,  G.  indica,  Voltzia ,  and  several  species  of 

22  Seward  and  Walton  (1923),  p.  324. 


GEOLOGICAL  FRAMEWORK  OF  THE  SOUTH  ATLANTIC 


13 


Phyllotheca  and  Dadoxylon,  evidently  an  Ecca-Beaufort  flora.  The 
highest  beds,  exposed  on  the  eastern  side  of  Falkland  Sound,  have 
yielded  Neocalamites  carrerei  (Zeill.),  suggestive  of  a  Triassic  age. 

Dolerites,  just  like  those  injected  into  the  Karroo  system  at  the 
close  of  the  Rhaetic,  pierce  the  strata  at  a  number  of  places,  signifi¬ 
cantly  avoiding  the  northern  folded  belt,  but  frequently  possessing  a 
northeast-southwest  trend.  Not  improbably  the  westerly  to  north¬ 
westerly  directed  foldings  correspond  in  age  with  those  striking 
nearly  east-west  in  the  Cape,  which  we  know  were  initiated  at  the 
very  close  of  the  Palaeozoic,  but  were  renewed  in  mid-Cretaceous 
times,  and  from  which  dolerite  is  absent.  The  Western  Province 
of  the  Cape  displays  in  addition  another  set  of  foldings  trending 
southwest  or  west-southwest. 

The  precise  place  of  the  Falkland  Islands,  stratigraphically, 
lithologically,  and  structurally,  with  reference  to  the  Cape  and  to 
Argentina,  will  be  discussed  at  a  later  stage  (Chapter  VI),  when  it 
will  be  shown  that  they  display  characters  consistently  intermediate 
between  those  of  the  two  countries,  though  somewhat  more  closely 
allied  with  the  former. 

SECTION  C.  SOUTH  AMERICA23 

Commencing  in  the  north,  the  outstanding  feature  is  the  great 
syncline  of  Lower  Pakeozoics,  much  covered  by  Tertiary  and  Quater¬ 
nary  deposits,  in  the  Amazon  Valley,  trending  eastward  from  Manaos 
to  Para,  in  which  direction  its  axis  deviates  towards  east-northeast. 
In  this  trough  marine  strata  of  Silurian,  Devonian,  and  Carbonif¬ 
erous  ages  are  all  involved,  resting  upon  the  Archaean,  which  bounds 
the  structure  for  immense  widths,  both  to  north  and  south. 

Eastward  in  Maranhao,  Piauhy,  Ceara,  Parnahyba,  and  Pernam¬ 
buco  there  is  a  wide  fringe  of  Tertiaries,  and  no  Palaeozoics  are  known 
to  occur,  if  we  ignore  the  rather  doubtful  series  of  Serra  Grande,  while 
inland  in  the  first  two  States  Permian  and  Triassic  Gondwana  sedi¬ 
ments  spread  over  a  wide  area,  reposing  mainly  on  crystallines.  In 
Alagoas,  Sergipe,  and  the  adjoining  part  of  Bahia  undoubted  Permian 
and  possibly  upper  Carboniferous  form  belts  rest  on  the  (probably) 
pre-Devonian  basement  and  display  a  certain  amount  of  folding. 
Save  for  them  and  the  similar  patch  in  the  southern  end  of  Bahia, 
Gondwana  beds  do  not  reach  the  coast  of  Brazil,  except  in  the  neigh¬ 
borhood  of  Torres. 

Inland  from  Bahia  is  an  extensive  trough  of  folded  lower  Palaeo¬ 
zoic  beds — mainly  slates  and  limestones,  probably  Ordovician — as 
well  as  much  older  formations,  striking  southwestward  from  near  the 
great  bend  in  the  Rio  Sao  Francisco,  following  up  the  valley  of  that 
river  almost  to  the  boundary  of  Minas,  which  feature  is  continued 


23SeeBranner  (1915)  (1919). 


14  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

beyond  with  similar  trend  through  Sao  Paulo  and  Parana  in  the  more 
closely  folded  and  altered  condition  to  reappear  in  Uruguay.  This 
lengthy  tectonic  structure,  running  approximately  parallel  to  the 
Atlantic  coast,  has  been  termed  the  “Brasilides”  by  Keidel. 

Occupying  the  whole  of  the  Upper  Parana  drainage  area  is  the 
great  but  shallow  “Parana  Basin,”  made  of  Gondwana  beds,  called 
the  Santa  Catherina  system,  deposited  upon  a  platform  of  crystal¬ 
lines  and  folded  Ordovician,  but  in  parts  of  Parana  and  Matto 
Grosso  upon  nearly  horizontal  lower  Devonian  strata  like  those  of 
the  Cape;  its  boundaries  have  been  determined  by  erosion  on  all 
sides  except  to  the  west  of  the  Paraguay  and  Lower  Parana  Rivers, 
where  the  beds  disappear  beneath  the  geologically  recent  Neogene 
formations.  A  large  part  of  east-central  Brazil  is,  furthermore, 
covered  by  horizontal  Cretaceous  and  perhaps  Tertiary  sandstones 
of  continental  type,  in  places  concealing  the  Santa  Catherina  beds. 

Passing  over  the  wide  stretch  in  Eastern  Argentina,  beneath 
which  these  Gondwana  strata  have  been  proved  by  deep  borings, 
those  beds  reappear  in  the  west  at  intervals  within  a  huge  region  from 
Bolivia  southward  to  Cordoba  and  Mendoza,  where  they,  together 
with  Palaeozoics  beneath  and  Cretaceo-Tertiaries  above,  have  been 
involved  in  the  Andine  movements,  with  general  strike  either  north 
or  a  little  east  of  north ;  here  they  are  known  as  the  Paganzo  system. 
Farther  to  the  south  similar  strata,  from  Devonian  to  Permian  in 
age,  build  the  ranges  between  Buenos  Aires  and  Bahia  Blanca  with 
southeasterly  trend,  structures  termed  the  “  Gondwanides  ”  by 
Keidel24  and  regarded  by  him  as  the  continuation  of  the  Southern 
Fold  ranges  of  the  Cape,  involving  as  they  do  precisely  similar 
and  equivalent  formations. 

The  equivalent  systems  of  Santa  Catherina  and  Paganzo  gener¬ 
ally  begin  with  a  glacial  formation,  which  corresponds  with  the 
Dwyka  tillite  of  South  Africa  and  is  followed  by  plant-  and  often 
coal-bearing  lower  Permian  beds  with  the  “  Glossopteris  flora”  and  by 
higher  Triassic  and  Rhaetic  rocks,  but  an  important  intraformational 
break  exists,  extending  perhaps  over  most  of  the  region.  At  the  top 
come  the  enormously  widespread  basaltic  effusions  of  Parana, 
though  not  restricted  to  that  region,  being  also  represented  in 
Maranhao  and  in  certain  of  the  remnants  in  the  pre-Cordillera  as 
well  as  in  Patagonia,  where,  however,  the  bulk  of  the  volcanics 
appear  to  be  of  acid  composition,  largely  overlain  by  nearly  flat 
lying  Cretaceous  and  Tertiary  beds. 

The  western  limits  of  Gondwanaland  are  not  exactly  known,  as 
the  Andine  belt  is  largely  composed  of  Mesozoic  marine  beds  and 
volcanics,  all  intensely  folded  and  injected  with  igneous  matter. 


24 Keidel  (1916  and  1922). 


GEOLOGICAL  FRAMEWORK  OF  THE  SOUTH  ATLANTIC  15 

SECTION  D.  GENERALIZED  COMPARISONS  BETWEEN 
THE  TWO  CONTINENTS 

Confining  attention  in  each  case  to  a  strip  some  45  degrees  in 
length  by  10  in  breadth,  we  shall  now  proceed  to  compare  the  two 
stretches,  namely,  the  tract  extending  from  Sierra  Leone  to  Cape 
Town  on  the  one  side  with  that  from  Para  to  Bahia  Blanca  on  the 
other ;  furthermore,  whenever  the  direction  of  any  structural  feature 
has  to  be  mentioned,  such  will  be  given  with  reference  not  to  the 
meridian,  but  to  the  coast-line  near  at  hand. 

In  each  continent: 

(1)  The  foundation  rocks  consist  of  crystallines  of  pre-Cambrian 
age  and  certain  belts  of  infolded  pre-Devonian  sediments  of  various 
though  mostly  undetermined  ages,  but  generally  corresponding 
lithological  characters, 

(2)  In  the  extreme  north,  marine  Silurian  and  Devonian  beds, 
only  slightly  disturbed,  rest  unconformably  upon  this  complex, 
occupying  a  broad  syncline  trending  obliquely  to  the  coast-line, 
namely,  between  Sierra  Leone  and  Gold  Coast  and  underlying  the 
estuary  of  the  Amazon. 

(3)  Farther  to  the  south,  belts  of  Proterozoic  and  early  Palaeo¬ 
zoic  strata,  mainly  quartzites,  slates,  and  limestones,  strike  nearly 
parallel  to  the  coast,  being  gently  flexed  in  the  north,  but  becoming 
more  disturbed  toward  the  south,  where  they  are  invaded  by  granitic 
masses,  for  example,  in  the  region  between  Liideritz  and  Cape  Town 
and  that  between  the  Rio  Sao  Francisco  and  Rio  La  Plata. 

(4)  Corresponding  to  the  nearly  flat-lying  Devonian  of  Clan- 
william  is  its  all  but  identical  counterpart  in  Parana  and  Matto 
Grosso. 

(5)  More  to  the  south  we  find  the  Devono-Carboniferous  of  the 
southern  Cape  paralleled  by  the  terrain  appearing  a  little  to  the  north 
of  Bahia  Blanca,  passing  up  conformably  into  the  Carboniferous 
glacials  and  Permian  sediments,  both  successions  having  been 
intensely  crumpled  under  Permo-Triassic  and  Cretaceous  move¬ 
ments  that  display  similar  orientations. 

(6)  Traced  northward,  the  tillites  in  each  case  become  horizontal 
and  transgress  across  the  Devonian  to  rest  upon  a  glaciated  pene¬ 
plain  formed  by  these  and  by  older  rocks ;  farther  to  the  north  they 
fail. 

(7)  The  glacials  are  in  each  case  overlain  by  continental  Permian 
and  Triassic  strata  with  the  “  Glossopteris  flora,  ”  covering  enormous 
areas,  followed  by  vast  outpourings  of  basalts  and  penetrated  on  an 
extensive  scale  by  dolerites  of  presumed  Liassic  age. 

(8)  These  Gondwana  beds  extend  northward  from  the  Southern 
Karroo  to  the  Kaokoveld  and  from  Uruguay  to  Minas  Geraes. 

(9)  Further  great  detached  areas  occur  in  the  north,  in  each  case 


16  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

some  distance  inland,  in  the  Angola-Congo  and  the  Piauhy-Maran- 
hao  regions. 

(io)  An  intraformational  break  is  widespread,  though  commonly 
there  is  no  angular  unconformity  between  late  Triassic  and  early 
Permian  beds.  In  certain  areas,  however,  the  former  may  rest  with 
visible  discordance  on  tilted  Permian  or  pre-Permian  formations. 

(n)  Tilted  Cretaceous  beds  occur  on  the  coast  only  in  the  Ben- 
guella-Lower  Congo  and  Bahla-Sergipe  areas. 

(12)  Horizontal  Cretaceo-Tertiary,  both  marine  and  continental, 
cover  great  extents  between  Cameroons  and  Togoland  and  in  Ceara, 
Maranhao,  and  also  more  to  the  south,  while  the  extensive  deposits 
of  the  Kalahari  can  roughly  be  paralleled  with  the  Neogene  and  the 
Quaternary  Pampean  of  Argentina. 

(13)  In  setting  down  this  generalized  summary,  the  important 
link  constituted  by  the  Falkland  Islands  must  not  be  overlooked. 
Their  folded  Devono-Carboniferous  succession  is  all  but  indistin¬ 
guishable  from  that  of  the  Cape,  while  the  Lafonian  closely  parallels 
the  Karroo  system.  Strati  graphically  and  structurally  the  Falklands 
have  their  place  with  the  southwest  of  the  Cape  and  not  with  Patagonia 
(Chapter  VI) . 

(14)  From  the  palaeontological  viewpoint,  attention  should  be 
focussed  on:  ( a )  the  “austral  facies”  of  the  Devonian  of  the  Cape, 
Falklands,  Argentina,  Bolivia,  and  Southern  Brazil,  in  contrast  to 
the  “boreal  facies”  of  northern  Brazil  and  central  Sahara;  ( h )  that 
unique  reptilian  genus  Mesosaurus  from  the  Dwyka  shales  of  the 
Cape  and  Iraty  shales  of  Brazil,  Uruguay,  and  Paraguay;  ( c )  the 
Gangamopteris-Glossopteris  flora,  with  a  small  admixture  of  northern 
forms  within  the  Lower  Gondwana  beds  in  the  south  of  each  country ; 
(d)  the  Thinnfeldia  flora  of  the  Upper  Gondwana  of  the  Cape  and 
Argentina;  ( e )  the  Neocomian  (Uitenhage)  fauna  in  the  south  of  the 
Cape  and  northwest  of  Neuquen  in  Argentina;  (/)  the  Northern  or 
Mediterranean  facies  of  the  Cretaceous  and  Tertiary  faunas  north 
of  the  Tropic  of  Capricorn;  and  (g)  the  South  Atlantic- Antarctic 
facies  of  the  Eocene  (San  Jorge  formation)  of  Patagonia. 

(15)  The  geographical  outlines  of  Africa  and  South  America  are 
amazingly  similar,  not  only  in  the  main,  but  even  as  to  detail ;  more¬ 
over,  excepting  in  the  north,  the  fringe  of  Tertiaries  is  of  small  width 
and  the  presence  of  those  beds  of  little  moment  therefore. 

On  following  the  various  groups  embraced  between  the  Devonian 
and  the  Rhaetic  of  the  two  continents  in  a  direction  away  from  the 
Atlantic  shores  an  amazing  generalization  shows  itself,  namely,  that 
the  variation  in  facies  of  these  several  formations  commonly  dis¬ 
closes  greater  divergences  within  distances  of  say  from  5  to  1 5  degrees 
of  arc  than  those  actually  noticed  on  comparing  the  developments 


Ti 


European  equivalents 

Cape  Province 

Falkland  Islands 

Sierra  de  la  Ventana 

Liassic. 

r 

be 

(h 

<u 

’  Basalts. 

Rhaetic. 

Cave  sandstone. 

o 

Red  beds. 

Triassic. 

-4— 1 

CO 

k  Molteno  beds. 

s 

Beaufort. 

• 

0) 

4-J 

GO 

>> 

o 

o 

’  Sandstones  and 
shales. 

Permian. 

fc 

d 

M 

Ecca. 

a 

<D 

C/3 

>> 

C/3 

a  * 
a 

•  H 

Shales,  clay- 
stones,  etc. 

Pillahuinc6  beds. 

Upper  Carboniferous. 

Dwyka 

'  White  band. 

Upper  shales. 

Glacials. 

O 

>1 

Shales,  sand¬ 
stones,  etc. 

.  Glacials. 

Shales. 

Glacials. 

Lower  shales. 

Middle  and  lower 

l 

Carboniferous  and 
middle  Devonian. 

Lower  Devonian  and 
uppermost  Silurian. 

Cape  system 

_ /V _ _ _ _ _ _ _ _ 

Witteberg  quartzites 
and  shales. 

Bokkeveld  beds  (fossil  - 
iferous) . 

Table  Mountain  sand¬ 
stones. 

Quartzites,  sand¬ 
stones,  and  shales. 

Fossiliferous  shales 
and  sandstones. 

Barren  sandstones. 

Greywackds. 

Fossiliferous  slates. 

Sierra  de  la  Ventana 
quartzites. 

* 


Paganzo  system 


European  equivalents 

Cape  Province 

Falkland  Islands 

Sierra  de  la  Ventana 

Liassic. 

be 

1-4 

03 

vO 

8 

Basalts. 

Rhaetic. 

Cave  sandstone. 

Triassic. 

o 

+-> 

CO 

Red  beds. 

.  Molteno  beds. 

* 

e 

Beaufort. 

03 

4-» 

03 

>> 

03 

o 

o 

Sandstones  and 
shales. 

a 

03 

03 

03 

Permian. 

b 

cj 

M 

Ecca. 

a 

03 

-*-> 

03 

03 

a  ■ 

Shales,  clay- 
stones,  etc. 

Pillahuinc6  beds. 

0 

N 

§ 

be 

Cj 

P-t 

Upper  Carboniferous. 

ca 

44 

White  band. 

Upper  shales. 

a 

'£ 

i 

41 

Shales,  sand¬ 
stones,  etc. 

Shales. 

& 

Q 

Glacials. 

.  Glacials. 

Glacials. 

Lower  shales. 

Middle  and  lower 

Carboniferous  and 
middle  Devonian. 

Lower  Devonian  and 
uppermost  Silurian. 

6 

03 

4-> 

03 

03 

< V 

Oh 

a 

O 

Witteberg  quartzites 
and  shales. 

Bokkeveld  beds  (fossil- 
iferous) . 

Table  Mountain  sand¬ 
stones. 

Quartzites,  sand¬ 
stones,  and  shales. 

Fossiliferous  shales 
and  sandstones. 

Barren  sandstones. 

Greywackds. 

Fossiliferous  slates. 

Sierra  de  la  Ventana 
quartzites. 

Table  I. — Strati  graphical  Table  Showing  the  Devono-Lias  Succession  in  South  America  and  South  Africa 

(The  wavy  line  indicates  an  unconformity.) 


San  Juan — La  Rioja 


V.  Red  conglomerate, 
etc. 

IV.  “Rhaetic.” 


III.  Stage. 


1 1.  Stage. 


Shales,  etc. 
Glacials. 

Cardiopteris  beds. 
Glacials. 


Barreal 


V.  Red  conglomerate. 
IV.  “Rhaetic.” 


03 

a; 

’G 

<D 

03 

3 

g  Glacials. 

o 


Marine  beds  with  Produc- 
tus  and  Spirifer. 


Slates,  greywack6s,  and  sandstones. 


o 

•  ’ — i 

<D 

Q) 

m 


Northern  Argentina  and 
Southern  Bolivia 


Marls. 

Limestone  and  Dolomite. 


Upper  sandstones  (Macha- 
reti). 

Mandiyuti. 

Oquita. 


Materal. 


Productus  beds. 

Sica-sica  beds. 
Huamampampa  sandstones. 
Conularia  and  Crinoid  beds. 
Ida  sandstones. 


03 

Cj 

.£ 

<v 

rX 

4-5 

a 

O 


Parand  Basin 


Serra  Geral  volcanics. 
Botucatti  sandstone. 

Rio  do  Rasto. 


Estrada  Nova. 

(upper  part) 


Estrada  Nova. 

(lower  part) 


Irat£. 


f  Palermo. 
<u  i 

11: 

'g  r 

jg  j  Glacials. 


Bonito. 


Ponta  Grossa  shales. 
Furnas  sandstone. 


a 

P-, 


Maranhao 


.|3  f  Basalts. 

*2  I  Red  sandstones. 


(?) 


Southwest  Africa 


North 


bo 

g  ( Basalts. 

43 


o 

•M 

CO 


Kaoko  beds. 


{Shales  and  sand¬ 
stones  with 
Psaronius. 


South 


bo 

<D 

43 


O 

W 


Basalts. 


Ecca. 


0) 

44 

£ 

Q 


White  band. 
Upper  shales. 
Glacials. 


Transvaal 


bo 

1-4 

<v 

rO 


CO 


S 

03 

03 

03 

o 

o 

i 


ni 

o 

y 

W 


Basalts. 

Bushveld  sandstone 
Bushveld  marls. 


Coal  measures. 


stf  r 
44 

b  1  Glacials. 

q! 


GEOLOGICAL  FRAMEWORK  OF  THE  SOUTH  ATLANTIC 


17 


nearest  the  two  opposed  shores,  although  the  ocean  between  is  no 
less  than  from  40  to  70  degrees  in  breadth.  This  observed  arrange¬ 
ment  is  considered  to  constitute  the  most  telling  argument  in  favor 
of  the  conception  that  the  two  continental  masses  were  in  the  past 
geographically  closer  to  each  other ,  which  is  actually  the  keynote  of 
the  Displacement  or  Disruption  Hypothesis.  Evidence  for  this 
momentous  assertion  will  be  found  in  the  following  pages  and  the 
problem  reviewed  in  Chapter  VII. 

For  convenience,  the  accompanying  correlation  table  has  been 
introduced  at  this  stage  to  indicate  the  stratigraphical  succession  in 
the  type  areas  to  be  dealt  with  in  detail  below. 


CHAPTER  III 

ARGENTINA  AND  BOLIVIA 

SECTION  E.  THE  SIERRAS  OF  THE  DISTRICT  OF  BUENOS  AIRES 

Rising  out  of  the  plain  of  Pampean  deposits  (late  Tertiary  to 
Quaternary),  here  close  upon  200  meters  above  sea-level,  are  the  two 
well-known  chains  of  ancient  rocks  lying  to  the  south  and  southwest 
respectively  of  Buenos  Aires. 

(1)  The  Sierra  de  Tandil25 

The  first  of  these  stretches  from  Mar  del  Plata  on  the  Atlantic 
coast  in  a  direction  a  little  to  the  west  of  northwest  past  Tandil  to 
Olavarrfa — a  distance  of  over  300  km.  with  a  mean  breadth  of  about 
50  km. — being  composed  of  a  series  of  small  chains  and  isolated 
hills  with  frequent  interruptions  and  nowhere  exceeding  an  altitude 
of  450  meters.  The  features  displayed  are  those  of  a  buried  and 
partially  exhumed  mountain  chain,  and  along  its  margins  the  belt  is 
bordered  by  inkers  of  the  hard  rocks  projecting  through  the  soft 
mantle  of  the  plain. 

!  The  formation  consists  largely  of  pre-Palasozoic  granite,  on  which 
rests  unconformably  a  basal  quartzitic  member  followed  by  dolomite, 
quartzite,  slate,  white  limestone,  etc.,  to  a  thickness  of  fully  150 
meters.  In  contrast  to  the  distinctly  younger  beds  of  the  Sierra  de  la 
Ventana,  the  strata  in  the  Sierra  de  Tandil  are  but  gently  flexed,  and 
are  often  lying  nearly  flat,  the  harder  members  producing  table- 
topped  hills;  on  the  coast  the  nearly  horizontal  quartzites  have 
determined  Cape  Corrientes.  This  flexuring  follows  two  directions 
mainly,  namely,  west -northwest  to  east-southeast  and  one  almost  at 
right  angles  thereto,  i.e.}  north-northeast  to  south-southwest.  The 
latter  represents  the  mid-Palaeozoic  “Brasilides,  ”  as  Keidel  has 
called  them,  which  have  been  crossed  and  modified  here  by  the  first- 
mentioned  set  of  the  Permo-Triassic  ‘  ‘  Gondwanides,  ’  ’  so  finely 
displayed  in  the  belt  to  the  southwest,  which  foldings,  although  of 
considerable  intensity  in  that  quarter,  seem  to  have  faded  out  to  the 
northeast  before  reaching  Uruguay. 

Where  seen  by  me  in  one  of  the  outliers  of  the  Dos  Hermanos 
(“The  Two  Brothers”),  near  Olavarrfa,  the  quartzites,  resting  on  a 
pedestal  of  red  granite,  are  white,  hard,  and  fine-grained,  though 
somewhat  coarser  at  their  base  and  not  unlike  the  Kuibis  quartzites 
of  the  Nama  system  of  Southwest  Africa,  that  are  also  followed  by 
slates  and  limestones.  They  are,  however,  presumed  to  be  of  Silurian 

25 Aguirre  (1879);  Hauthal  (1896,  1901);  Valentin  (1894);  and  Nagera  (1919),  who 
gives  a  bibliography. 


18 


ARGENTINA  AND  BOLIVIA 


19 


or  more  probably  of  Ordovician  age,  because  of  impressions  referred 
to  Arthropliycus  harlani  Hall,  in  certain  of  the  quartzites  at  Balcarce 26 
while  Siemiradski  reported  finding  Stromatopora  and  A  try  pa  in  the 
dolomitic  group,27  though  such  does  not  appear  to  have  been  con¬ 
firmed. 

It  should  be  observed  that  this  belt  stands  wholly  isolated  in  the 
Pampean  formation,  that  it  is  over  400  km.  distant  from  the  possibly 
equivalent  strata  in  Uruguay  and  150  km.  from  the  Palaeozoics  of 
the  Sierra  de  la  Ventana  and  Pillahuinco,  and  that  the  few  bore-holes 
that  have  penetrated  the  Pampean  covering  have  only  proved 
granite ;  for  example,  that  at  Buenos  Aires  and  at  Telen  in  the  district 
of  La  Pampa  to  the  west. 

(2)  The  Sierra  de  la  Ventana 

The  Fold-ranges,  among  which  is  embraced  this  most  important 
of  the  sierras,  lie  not  far  to  the  north  of  Bahia  Blanca  and  occupy  a 
tract  some  180  km.  long  by  50  km.  at  its  widest.  They  include  the 
Sierra  de  Puan,  Sierra  del  Chaco,  and  Sierra  de  la  Ventana  proper  in 
the  southwest  and  west,  and  the  Sierra  de  Bravard,  Sierra  de  las 
Tunas,  and  Sierra  de  Pillahuinco  on  the  northeast,  and  make  a 
sweeping  double  curve  with  general  strike  from  southeast  to  north¬ 
west,  bending  to  the  west  in  the  latter  direction.  In  the  heart  of  the 
ranges  the  Rio  Sauce  Grande  courses  along  a  strike  valley  that 
generally  follows  the  Tillite  zone.  As  with  the  Sierra  de  Tandil,  the 
Pampean  formation  laps  around  the  base  of  the  rising  ground  and 
enters  many  of  the  valleys. 

The  geology  has  been  described  by  Aguirre,  Hauthal,  and 
Schiller,28  and  more  particularly  by  Keidel,29  who  has  not  only  given 
the  most  detailed  and  accurate  account,  but  by  the  discovery  of  the 
Carboniferous  tillite  was  first  able  to  point  to  the  wonderful  simi¬ 
larity  with  South  Africa  and  show  that  the  ranges,  structurally  as 
well  as  geologically,  appeared  to  form  the  continuation  across  the 
Atlantic  of  the  Fold-ranges  of  the  Cape  Western  Province.  The 
writer’s  researches  bear  out  the  value  of  Keidel’s  work  and  percep¬ 
tion,  for  in  only  one  essential  does  his  interpretation  differ  from  that 
of  this  Argentine  geologist,  namely,  in  the  stratigraphical  position  of 
the  Pillahuinco  beds.  To  the  visitor  from  South  Africa  the  resem¬ 
blances  with  that  country  are  simply  astounding,  such  being  the  case 
not  only  with  the  major  elements,  but  in  so  many  minor  respects,  as 
well  as  in  lithological  details  regarding  the  tillite  and  in  the  presence 
and  attitude  of  the  Tertiary  “high-level  gravels.” 

The  cross-section  from  southwest  to  northeast  passing  through 

26Ndgera  (1919a),  p.  7. 

27  Siemiradski  (1893). 

28 Aguirre  (1891);  Hauthal  (1892,  1896,  1901,  1904);  Schiller  (1907). 

29  Keidel  (1916),  also  (1922). 


20  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 


a> 

two 

d 

> 


the  railway  station  of  Sierra  de  la  Ventana  (formerly  called  Rio 
Sauce  Grande)  would  show  (Fig.  i)  on  the  southwest  a  closely  folded 

and  inverted  succession  of  Palaeozoic  strata 
in  which  the  softer  beds  display  a  strong 
cleavage  that  is  dipping  at  a  high  angle 
to  the  southwest  (shown  by  broken  lines 
in  the  diagram). 

The  lowest  member — a  thick,  whitish, 
quartzitic  sandstone  formation,  the  equiv¬ 
alent  of  the  Table  Mountain  sandstone  of 
the  Cape — builds  the  main  range,  which 
in  its  various  aspects  strongly  recalls  the 
chains  of  the  Langebergen,  Outeniqua,  and 
other  coastal  barriers  of  the  Cape,  and 
which  culminates  in  the  Cerro  de  los  Tres 
Picos  (1,280  meters);  farther  along  the 
crest  is  the  peak  pierced  by  the  famous 
“ventana”  or  window,  from  which  the 
range  takes  its  name.  On  its  southwestern 
foot  the  basement  granite  is  reported  to 
crop  out  near  Tomquist  and  Aguas  Blan¬ 
cas,  the  contact  being  an  inverted  one 
apparently.  The  sloping  ground  to  the 
northeast,  for  a  distance  of  some  5  or  6 
km.  down  to  the  valley  of  the  Rio  Sauce 
Grande,  is  made  by  the  second  member ,  a 
series  of  cleaved  slates  and  greywackes, 
corresponding  to  the  Bokkeveld  and 
Witteberg  series  of  the  Cape,  in  which 
the  folding  can  at  times  be  made  out,  while 
the  valley  floor,  together  with  the  rising 
ground  just  beyond,  is  composed  of  a 
cleaved  greenish  tillite,  the  representative 
of  the  Dwyka  glacials. 

The  stratigraphical  position  of  the 
strata  to  the  northeast  has  hitherto  been 
in  doubt,  the  folded  quartzites  and  slaty 
beds  of  the  Sierra  de  Pillahuinco  having 
been  regarded  by  Schiller  as  the  equiva¬ 
lent  of  those  in  the  ranges  to  the  south¬ 
west,  a  view  satisfactorily  disposed  of  by 
Keidel,  who  has  nevertheless  considered 
them  as  probably  of  pre-Devonian  age. 
My  observations,  however,  have  shown  an 
upward  passage  into  them  from  the  tillite, 


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ARGENTINA  AND  BOLIVIA 


21 


which  goes  to  indicate  that  these  beds  are  the  equivalent  of  the 
folded  Ecca  series  of  the  southwestern  part  of  the  Cape  Karroo 
and  of  the  Lafonian  of  the  Falkland  Islands,  as  will  be  discussed  in 
the  sequel.  While  the  entire  succession  is  thus  extraordinarily  simi¬ 
lar  to  those  in  the  Cape  and  Falklands,  its  resemblances  to  the 
equivalent  beds  represented  in  the  pre-Cordillera  of  San  Juan  to  the 
northwest  are,  it  should  be  noted,  by  no  means  so  clearly  marked. 

(a)  The  Infra-tillite  Succession — To  the  excellent  account  given 
by  Keidel 30  there  is  little  to  add.  The  basal  group  may  possibly  be 
close  on  1,000  meters  in  thickness,  but  the  intense  crumpling  in  this 
section  would  prevent  any  exact  measurements  being  made.  In  the 
splendid  exposures  at  the  head  of  the  Arroyo  San  Bernardino  the 
quartzites  (Fig.  i,  I )  are  isoclinally  folded  in  a  rather  regular  fashion, 
the  succession  being  of  course  an  inverted  one,  the  pressure,  just 
as  in  South  Africa,  having  come  from  a  southerly  direction.  Owing 
to  a  mishap  to  a  negative,  I  am  unable  to  give  a  photograph  of 
these  fine  contortions,  but  one  of  Beder’s  views,  published  by  Keidel, 
taken  further  to  the  west  along  the  same  range,  is  reproduced,  which 
will  serve  to  bring  out  this  feature  very  clearly  (Plate  I) . 

Most  of  the  beds  are  hard,  white,  fine-grained  quartzite,  but 
there  are  darker  and  faintly  greenish  varieties  and  a  number  of  thin, 
greenish-gray  schistose  quartzites  and  slaty  kinds  in  thinner  layers. 
One  conspicuous  shale  bed  (Plate  II,  A,  and  Fig.  i,  ia)  perhaps  a  few 
hundred  meters  from  the  top  of  the  series,  is  8  meters  thick,  a  dark- 
green,  silvery  slate,  with  base  well  defined,  which  invites  comparison 
with  the  well-known  ‘  *  shale  band  ”  of  the  Table  Mountain  sandstone, 
but  no  glaciated  pebbles  were  seen  in  it  or  just  below  it.  The  upper¬ 
most  hundred  meters  of  strata  are  distinctly  darker  than  those  com¬ 
posing  the  range  proper,  approaching  a  greywacke  in  some  respects, 
the  rock  being  schistose,  showing  some  false-bedding  and  including 
a  little  grit  with  quartz  fragments  and  pebbles,  which  was  the  only 
coarse  material  seen.  The  schistose  and  darker  character  tends  to 
obscure  the  upward  passage  into  the  slate  group,  which,  as  Keidel 
has  pointed  out,  is  rapid,  though  not  obvious.  That  the  quartzites 
underlie  the  slates  can  be  shown  by  a  study  of  their  folded  junction. 

To  sum  Up,  the  quartzites  have  marked  similarities  to  the  Table 
Mountain  series  of  the  Cape ;  not  to  that  in  the  Ceres  or  Clanwilliam 
districts,  but  to  the  facies  in  the  south,  i.e.,  Mossel  Bay,  George,  or 
Knysna,  where  it  is  finer-grained,  where  quartz  pebbles  are  rarer  and 
smaller,  and  where  thin  layers  of  dark  slates  are  not  unusual. 

In  the  overlying,  seemingly  thick,  group — called  the  ‘  ‘  esquistos 
by  Aguirre,  the  folding  can  now  and  again  be  made  out,  despite  the 
strong  cleavage.  The  lowest  beds  are  fine  slates,  with  some  bands 
of  greywacke  appearing  higher  up,  while  the  topmost  beds  consist 

10 Keidel  (1916),  pp.  11-12;  21-22;  28-29. 


22  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

not  of  quartzites,  as  in  the  Cape  and  Falklands,  but  of  highly  cleaved 
greywackes,  mostly  brownish  in  color  and  full  of  feldspar,  finer 
alternating  with  coarser  varieties,  the  latter  becoming  in  places  quite 
gritty,  while  a  few  pebbles  of  dark  bluish  quartzite  were  observed. 
The  marked  cleavage  obscures  both  the  dip  and  the  folding,  but 
the  topmost  bed,  in  contact  with  the  tillite,  is  a  hard,  brown,  un¬ 
cleaved  grit. 

These  strata  are  manifestly  the  equivalent  of  the  middle  and 
upper  divisions  of  the  Cape  system,  much  distorted  Devonian  fossils 
having  indeed  been  obtained  in  several  places  in  the  slaty  basal  por¬ 
tion  of  the  assemblage,  while  a  specimen  inclosed  in  a  sandy  rock 
approaching  a  greywacke,  which  is  exhibited  in  the  La  Plata  Museum, 
was  derived  from  this  locality.  The  greywacke,  marked  (. 2a )  in  the 
section  (Fig.  i),  is  evidently  the  same  bed  as  is  shown  on  Keidel’s 
map  of  the  territory  lying  a  short  distance  farther  to  the  northwest 
along  the  same  strike,  and  recalls  the  first  or  fossiliferous  sandstone 
of  the  Bokkeveld  series  and  the  Tibagy  sandstone  of  Parana.  The 
uppermost  group  of  greywackes  and  occasional  slates,  which  has 
so  far  yielded  neither  molluscan  nor  plant  remains,  is  wholly  differ¬ 
ent  from  the  white,  fine-grained  quartzites  with  green  slaty  interca¬ 
lations  of  the  Witteberg  series  or  those  occupying  a  similar  horizon 
in  the  Falklands,  and  in  this  very  important  respect  the  succession 
here  differs  from  those  in  South  Africa  and  the  Falkland  Islands. 

It  is  uncertain  whether  the  phyllites  and  greywackes  known  from 
the  Sierra  Pintada  in  the  southeastern  part  of  the  Mendoza  district 
are  of  Devonian  age,  but,  as  will  be  set  forth  later  on  (Chapter  VI), 
the  strata  in  Jachal  to  the  north  referred  to  this  epoch  and  containing 
the  typical  “austral  fauna”  in  their  upper  part,  are  in  their  basal 
section  no  longer  white  quartzites,  but  shaly  sandstones  and  sandy 
shales  with  bands  of  soft,  dark  sandstone  and  of  a  friable  nature. 
This  marked  difference  in  lithology  of  the  basal  portion  of  the 
Devonian  within  the  distance  of  less  than  1,000  km.  toward  the 
northwest,  as  compared  with  the  slight  change  noted  in  the  distance 
of  almost  6,000  km.  from  the  Cape  or  2,000  km.  from  the  Falklands 
can  not  be  overemphasized  and  will  be  discussed  in  Chapter  VII. 

( b )  The  Tillite — In  the  neighborhood  of  Sierra  de  la  Ventana 
station  the  lower  part  of  the  glacial  beds  (4a)  is  but  poorly  exposed 
over  the  gently  undulating  ground,  but  practically  continuous  out¬ 
crops  can  be  seen  in  the  higher  country  to  the  east  of  the  railway 
bridge  spanning  the  Rio  Sauce  Grande,  while  excellent  artificial 
sections  are  disclosed  in  the  railway  cuttings  between  kilometer 
posts  529  and  536.  The  total  breadth  of  the  belt  is  about  9  km. 
The  prevailing  strong  cleavage  (Plate  II,  B),  directed  southwestward 
at  an  average  angle  of  about  65°,  coupled  with  the  unsatisfied  charac¬ 
ter  of  the  deposit,  obscures  the  true  behavior  of  the  formation,  which 


ARGENTINA  AND  BOLIVIA 


23 


accounts  for  the  erroneous  interpretations  of  the  section  by  Hauthal 
and  others,  but  a  careful  study  of  the  attitude  of  certain  shaly  or  else 
quart zitic  layers  goes  to  indicate  that  the  formation,  though  seem¬ 
ingly  dipping  southwestward  beneath  the  greywackes  in  that  direc¬ 
tion,  is  actually  resting  upon  the  latter  and  as  a  whole  is  dipping 
northeastward  below  the  strata  of  the  Sierra  de  Pillahuinco.  On  the 
southwest  the  folds  are  isoclinal  with  axial  planes  dipping  southwest- 
ward  at  nearly  45 °,  but  along  the  Rio  Sauce  Grande  flattening  has 
occurred  and  thereafter  the  glacials  are  but  slightly  flexed,  to  pass 
ultimately  at  quite  a  low  angle  northeastward  beneath  the  sediments 
of  the  Cerro  Bonete.  I  agree  with  Coleman 31  that  Keidel 32  has  over¬ 
estimated  the  degree  of  folding  that  is  present  in  the  railway  section, 
since,  except  for  one  important  reversal  of  dip,  the  mass  is  inclined 
regularly  northeastward,  though  signs  of  strong  compression  are 
nevertheless  clear.  The  thickness  is  difficult  to  estimate  here,  because 
of  the  uncertainty  as  regards  that  of  the  lower  part  of  the  forma¬ 
tion,  but  it  is  undoubtedly  well  in  excess  of  the  figure  given  by 
Keidel,  namely,  60  meters;  it  would  seem  to  be  at  the  least  200 
meters,  perhaps  more. 

The  base  was  studied  on  the  left  side  of  the  Arroyo  San,  Ber¬ 
nardino,  a  few  kilometers  west  of  the  station,  the  nearest  point  where 
the  junction  with  the  hard  top  of  the  greywacke  group  (3)  is  exposed. 
A  careful  examination  showed  the  tillite  to  be  dipping  at  45  beneath 
the  greywacke,  but  within  the  latter  are  what  were  taken  to  be  two 
narrow  infolds  of  the  base  of  the  glacials,  certain  marginal  and  other 
characters  indicating  that  they  were  merely  the  repetition  of  one  and 
the  same  zone.  As  a  rule,  the  change  from  greywacke  to  dark-blue, 
fine-grained  tillite  with  small  inclusions  takes  place  within  a  distance 
of  a  few  centimeters,  while  some  small  pebbles  occasionally  occur 
just  within  the  greywacke  itself.  At  one  place  a  wedge  of  soft 
schistose  strata  appears  just  within  the  latter,  including  some  iso¬ 
lated  pebbles  like  those  in  the  tillite,  all  of  which  makes  it  practi¬ 
cally  assured  that  there  is  a  perfectly  conformable  transition  from  the 
arenaceous  into  the  glacial  formation.  This  conclusion,  therefore, 
confirms  the  opinions  arrived  at  by  both  Hauthal  and  Keidel. 

The  condition  thus  parallels  that  in  the  south  of  the  Cape  (south 
of  latitude  330)  where  no  discordance  has  been  detected,  though  the 
change  from  the  one  formation  to  the  other  is  often  quite  abrupt,  but 
differs  from  those  in  the  Tanqua  Karroo  or  in  the  Falklands,  where 
the  tillite  rests  upon  a  slightly  striated  surface  of  the  underlying 
Carboniferous  quartzites. 

Of  the  glacial  origin  of  the  formation,  a  discovery  first  made  by 
Keidel  and  since  confirmed  by  Coleman,  there  can  not  be  the  slightest 
doubt.  All  the  phenomena  displayed  duplicate  down  to  minutest 

81  Coleman  (1918),  p.  319*  82 Keidel  (1916),  P-  25- 


24  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

detail  those  characterizing  the  Dwyka  tillite  in  the  south  of  the 
Karroo.  The  rock  is  a  hard  greenish  unstratified  material,  having 
scattered  irregularly  and  sometimes  rather  sparsely  through  it  inclu¬ 
sions  that  rarely  exceed  0.5  meter  in  length.  Among  the  host  of  rock 
types  represented,  Keidel  discovered  a  lump  of  fossiliferous  limestone, 
while  noteworthy  are  certain  quartzites  and  greywackes  indistin¬ 
guishable  from  those  of  the  Sierra  de  la  Vent  ana,  but  it  is  important 
to  observe  in  the  uncleaved  condition.  Keidel  also  mentions  erratics 
of  material  like  the  beds  in  the  Sierra  de  Pillahuinco,  but  I  could  find 
nothing  that  could  with  any  confidence  be  ascribed  to  those  forma¬ 
tions  exposed  to  the  northeast.  Well-striated  and  often  faceted 
boulders,  such  as  are  typical  of  glacial  tills,  can  be  obtained  without 
difficulty,  such  as  have  been  figured  by  Keidel  and  Coleman. 

Like  the  Dwyka  along  the  south  of  the  Karroo,  the  Rio  Sauce 
Grande  conglomerate  is  not  one  uninterrupted,  single  body  of 
morainic  matter,  for  there  are  several  surfaces  of  discontinuity,  which 
evidently  mark  the  cessation  and  subsequent  renewal  of  glacial 
activity.  At  kilometer  535  in  a  railway  cutting  is  exposed  the 
sharply  defined  top  to  a  tillite  body  with  a  thin,  splintery  shale  rest¬ 
ing  upon  the  plane  or  break  and  passing  up  in  turn  into  a  normal 
tillite.  A  little  higher  up  there  appears  a  “ gravelly”  band  of  the 
kind  of  material  termed  in  South  Africa  “gravel  Dwyka,”  charged 
with  small  angular  and  sub-angular  stones,  while  next  in  turn  comes 
an  instance  of  a  “boulder  pavement”  in  which  the  inclusions  within 
the  top  of  the  lower  body  of  morainic  material  have  all  been  pressed 
down  to  one  level  and  striated  in  a  direction,  so  far  as  can  be  made 
out,  north  65°  west  (true) ;  this  is  overlain  by  normal  tillite.  The  way 
in  which  the  top  of  each  of  these  pebbles  just  rises  above  the  surface 
of  discontinuity,  and  other  features,  show  that  the  phenomena  are 
due  to  the  overriding  of  the  moraine  by  the  ice  itself  and  are  not  due 
to  subsequent  tectonic  movements.  Boulder  pavements  of  identical 
character  have  been  recorded  in  the  Dwyka  and  in  the  Carboniferous 
glacials  of  Cape  Wynyard  in  Tasmania.  Furthermore,  there  is  a  very 
important  intercalated  zone  of  quartzitic  rocks  (Fig.  1,  4b ),  probably 
lenticular  in  habit,  with  a  maximum  thickness  of  40  meters,  which 
splits  the  tillite  mass,  occurring  on  a  horizon  about  70  meters  from 
the  top  of  the  glacials  building  up  the  outlying  peak  of  the  Cerro  de 
Pillahuinco  immediately  to  the  west  of  the  534  km.  post  and  seen 
again  on  the  railway  at  533.50  and  533  and  running  in  a  belt  1  km. 
to  the  east  on  the  left  side  of  the  Arroyo  Negro,  where  it  can  be  seen 
to  pass  below  the  upper  tillite  (4c).  At  53 1.2  km.  the  base  is  found  to 
be  an  intensely  hard,  gray,  small-pebble  conglomerate,  crammed  with 
inclusions — some  certainly  striated — resting  through  the  medium 
of  a  greenish,  thin,  and  variable  quartzite  on  the  lower  tillite,  a  break 

occurring  at  this  level.  This  is  the  band  whence  most  of  the  specimens 

\. 


ARGENTINA  AND  BOLIVIA 


25 


in  museum  collections  labeled  “tillite”  come  from,  though  it  is 
decidedly  not  representative. 

The  zone  itself  consists  of  this  hard  conglomerate,  followed  by 
brownish  to  greenish  quartzites  and  greywackes  possessing  feeble 
or  irregular  bedding,  with  some  softer  bands  allied  to  tillite.  The  zone 
recalls  some  of  the  quartzite  bands  and  lenses  in  the  southern  Dwyka, 
for  example,  some  near  Matjesfontein  station  in  the  Southern 
Karroo,  being  in  the  nature  of  interglacial  sands,  while  at  kilometer 
531.75  are  some  of  those  curious  quartzitic  “pseudo-boulders,  ”  such 
as  have  been  recorded  from  the  Cape  and  Natal,  representing  masses 
of  sandy  material  picked  up  by  the  ice  and  “balled  up”  during  the 
progress  of  the  glacier. 

The  upper  part  of  the  glacial  series  is  best  seen  along  the  road 
from  Sierra  de  la  Ventana  to  Peralta,  at  a  point  nearly  midway 
between  the  Cerro  de  Pillahuinco  and  the  Cerro  Bonete.  Here  the 
tillite  (4C)  becomes  finer  grained  and  more  cleaved,  inclusions  get 
isolated,  smaller,  and  at  length  fail  entirely,  and  the  rock  passes  up 
without  a  break  into  a  zone  (5)  about  100  meters  thick,  of  hard, 
cleaved  slates  of  blue-gray  color  characterized  by  little  ocherous 
concretions  due  to  the  oxidation  of  pyrite  or  marcasite,  and  these  in 
turn  into  the  group  of  sandstones,  greywackes,  flagstones,  and  quartz¬ 
ites  (1 6 )  building  the  Cerro  Bonete  and  the  hills  to  the  northeast  and 
north,  which  can  for  convenience  be  termed  the  “Pillahuinco  beds.  ” 

(c)  The  Strata  of  the  Sierra  de  Pillahuinco — This  is  the  only  point 
in  this  neighborhood  where  I  found  the  exposures  sufficiently  good  to 
show  the  passage  between  the  glacials  and  the  group  building  the 
Sierra  de  Pillahuinco,  the  age  of  which  has  hitherto  been  in  doubt.  It 
is  true  that  Keidel  recorded  the  superposition  of  the  latter  upon  the 
tillite  at  one  point,  which,  however,  he  took  to  be  due  to  thrusting, 
as  is  not  at  all  unlikely,  for  in  the  range  lying  a  few  kilometers  to 
the  northwest  from  kilometer  post  529  the  arenaceous  zone  near  the 
base  of  the  Pillahuinco  beds  seems  to  be  thrown  against  the  tillite 
by  faulting. 

The  strata  that  were  studied  between  the  Cerro  Bonete  and 
Peralta  station  consist  of  hard  gray-green  sandstones  and  quartzites, 
pale  in  the  coarser  and  generally  darker  in  the  finer-grained  vari¬ 
eties  ;  there  are  also  schistose  greywackes  and  some  thinner  shaly  and 
flaggy  bands  still  displaying  cleavage,  but  the  strata  as  a  whole  are 
very  different  from  the  Devono-Carboniferous  succession  to  the 
southwest.  To  the  east  of  the  railway,  Keidel  has  recorded  red  and 
green  slaty  beds,  often  blotchy,  and  beds  of  clayey  limestone  and 
marl  similar  to  those  observed  by  Schiller  on  the  northern  edge  of 
the  Sierra  de  Pillahuinco,  north  of  Peralta,  intercalated  with  the 
quartzites — probably  higher  zones  within  the  series. 

The  folding  in  the  Cerro  Bonete  is  gentle,  but,  followed  north- 


26  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

eastward,  it  becomes  more  intense.  While  asymmetrical  there,  as  is 
also  the  case  just  northwest  of  the  railway,  on  proceeding  northward 
the  folds,  as  Keidel  has  remarked,  become  overturned  to  the  south¬ 
west,  though  it  is  important  to  observe  that  the  crumpling  after¬ 
wards  decreases  and  that  opposite  Stegmann  Station  (507  km.)  the 
beds  are  now  practically  flat.  The  fact  that  the  pre-Devonian  strata 
of  the  Sierra  de  Tandil  are  so  little  disturbed  indicates  that  the 
“  Gondwanides  ”  must  be  fading  out  towards  the  northeast. 

The  parallel  is  extraordinarily  good  with  the  Ecca  series  of  the 
southwestern  Cape,  say  between  Laingsburg  and  Prince  Albert,  where 
the  foldings  die  out  in  a  northerly  direction  within  a  relatively  short 
distance.  The  southern  Ecca,  moreover,  contains  thick  groups  of 
hard  grayish  and  dark  greenish  sandstones,  almost  a  quartzite  in 
places,  and  much  flagstone  in  addition  to  hard  green  and  purple  mud¬ 
stones  and  shales  and  sometimes  impure  limestones.  The  unfossil- 
iferous  nature  of  the  Cape  beds  is  another  parallel,  for  in  the  brief 
search  possible  near  Peralta  only  worm  castings  were  seen  and  some 
poor  impressions  that  might  be  parts  of  plants.  A  further  examina¬ 
tion  of  these  beds  is  hence  extremely  desirable.  In  the  corresponding 
portion  of  the  Lafonian  system  of  the  Falklands,  Baker  has  also 
recorded  fine-grained  and  intensely  hard  greenish  sandstones,  and 
sometimes  typical  slates.  It  should  be  noted  that  the  carbonaceous 
shales  of  the  Dwyka  or  of  the  Iraty  series  do  not  appear  to  be  repre¬ 
sented,  but  they  are  certainly  missing  in  the  Falklands  and  probably 
too  in  the  district  of  San  Juan  to  the  northwest. 

id)  The  High-Level  Gravels — To  my  mind  the  most  striking  par¬ 
allel  with  the  Cape  is  formed  by  the  consolidated  gravels  and  breccias 
resting  on  benches  or  terraces  cut  along  the  inner  side  of  the  quartz¬ 
ite  chain  of  the  Sierra  de  la  Ventana  (Plate  III,  A).  Indeed,  viewed 
even  at  short  range,  I  had  great  difficulty  in  realizing  that  this  was 
another  continent  and  not  some  portion  of  one  of  the  southern 
districts  in  the  Cape,  say  Caledon,  Oudtshoorn,  or  Uniondale.  Taken 
in  conjunction  with  the  other  resemblances  already  mentioned,  the 
parallelism  is  so  wonderfully  close  that  one  can  not  escape  from  the 
conclusion  that  the  geological  histories  of  these  two  countries 
must  have  been  all  but  identical  from  mid-Palaeozoic  down  to 
early  Tertiary. 

As  Keidel 33  has  so  well  described,  and  exactly  as  in  the  Cape,  the 
highest  terrace  is  merely  a  shelf  incised  in  the  quartzites  beneath  the 
crest  of  the  range,  running  at  a  level  of  close  on  800  meters  above  the 
ocean.  The  second  has  an  altitude  varying  between  450  and  550 
meters,  cut  at  about  the  junction  of  the  quartzites  and  the  younger 
slates,  and  evidently  had  a  wide  distribution  formerly,  since  the 
spurs  of  slates  and  greywackes  between  the  valleys  leading  down  to 

33  Keidel  (1916),  pp.  37-42. 


ARGENTINA  AND  BOLIVIA 


27 


the  Rio  Sauce  Grande  show  all  the  characters  of  a  dissected  peneplain 
transecting  the  highly  tilted  Palaeozoics  and  sloping  from  the  range 
gently  toward  the  northeast.  In  places  this  terrace  still  bears  cap¬ 
pings  of  hard,  bright-red  conglomerates  and  breccias,  as,  for  example, 
at  the  head  of  the  Arroyo  San  Bernardino  below  the  Tres  Picos  (Fig. 
i ,  7)  where  the  deposit  is  composed  chiefly  of  subrounded  to  angular 
lumps  of  quartzite  coarsely  stratified  and  set  in  a  hard  arenaceous 
cement  colored  with  oxides  of  iron.  The  material  resembles  exactly 
in  its  character  and  habit  the  so-called  “high-level  gravels”  or 
“ferricretes”  of  the  southern  Cape;  comparison  might  be  made 
between  Keidel’s  Plates  IX  and  X  and  Plates  XXIII  and  XXIV 
in  Rogers  and  Du  Toit’s  Geology  of  Cape  Colony. 

Obviously  these  are  terrestrial  scree  and  gravel  deposits,  which, 
from  analogy  with  South  Africa,  were  formed  on  a  peneplain  carved 
out  during  the  early  part  of  the  Tertiary,  and  which  in  similar  fashion 
have  since  been  dissected  to  a  depth  of  from  100  to  200  meters,  as 
marked  by  accumulations  of  boulders  or  by  patches  of  younger 
gravels  at  various  levels  in  the  valleys.  This  in  the  Cape  was  due  to 
the  elevation  of  the  interior  of  the  continent  in  about  the  Miocene  or 
Pliocene.  In  Argentina,  however,  this  broken  country  subsequently 
became  in  great  part  buried  beneath  the  mantle  of  Pampean  loess. 

Attention  might  be  drawn  to  the  fact  that  in  the  neighborhood  of 
Bahia  Blanca  borings  have  disclosed  at  a  depth  of  about  600  meters 
beneath  marine  (probably  lower)  Tertiary  a  group  of  red  clays  and 
grey  and  white  marls  sloping  gently  to  the  southeast,  which,  although 
unfossiliferous,  are  regarded  as  upper  Cretaceous  from  their  resem¬ 
blance  to  strata  of  that  age  developed  in  Patagonia.34 

SECTION  F.  THE  SOUTHERN  PRE-CORD  1LLERAN  REGION 

As  Windhausen 35  has  pointed  out,  the  fold-belt  of  the  area  just 
described  is  doubtless  prolonged  to  the  northwest  beneath  the  Pam¬ 
pean  formation,  curving  somewhat  toward  the  north  in  that  direc¬ 
tion,  for  Gondwana  beds  appear  from  below  Pleistocene  basalts  and 
Triassic  volcanics  in  the  Sierra  Pintada  near  San  Rafael  on  the  Rio 
Atuel,  where  they  exhibit  a  north-northwesterly  strike. 

Unfortunately,  very  little  is  known  about  this  rather  important 
inlier,  though  Windhausen  has  mentioned  the  presence  of  a  tillite  and 
also  an  unconformity  at  the  base  of  the  Gondwana  beds,  but  the 
intensity  of  the  erosion  that  followed  the  late  Permian  foldings  is 
indicated  by  the  unconformity  between  these  and  the  succeeding 
Triassic  quartz-porphyries  and  tuffs.36 

It  would  appear  that  the  “  Gondwanides  ” — the  “Hercynian 
folds”  of  Groeber — extend  northward  into  Mendoza  and  San  Juan; 

34  Wichmann  (1918).  36  Windhausen,  p.  35;  Groeber  (1918),  p.  53. 

35  Windhausen  (1918),  p.  35. 


28  GEOLOGICAL  COMPARISON  OP  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

but  in  that  direction  the  strata  have  subsequently  become  involved 
in  the  younger  Andine  movements  with  a  north-south  strike  and  are 
much  affected  by  overturning  and  thrusting,  whereby  slices  of  differ¬ 
ent  formations  down  to  the  Tertiary  have  repeatedly  been  brought 
into  abnormal  relationships  with  one  another  and  the  continuity  of 
the  relatively  narrow  belts  of  Gondwana  frequently  interrupted. 
The  earlier  north-northwesterly  directed  flexures  can  nevertheless 
still  be  made  out  in  parts  of  San  Juan  and  Jachal.  Throughout  this 
region  the  Gondwana,  known  as  the  “Paganzo,  ”  rests  unconforma- 
bly  upon  the  Devonian  or  upon  older  formations. 

(1)  The  Glacial  Beds  of  San  Juan  and  Jachal 

At  the  foot  of  the  Sierra  Chica  de  Zonda,  to  the  south  of  the  town 
of  San  Juan,  various  strata  have,  through  the  labors  of  Stappenbeck, 
Bodenbender,  and  Keidel,37  long  been  known  to  crop  out,  containing 
examples  not  only  of  Carboniferous  plants,  but  of  the  Glossopteris 
flora,  and  also  glacial  beds.  It  becomes  important,  therefore,  to  con¬ 
sider  the  precise  relationships  of  the  formations  involved,  in  view 
particularly  of  the  opinion  expressed  by  Keidel  that  there  are  two 
distinct  plant-bearing  groups,  the  one  pre-Gondwana  with  European 
Carboniferous  forms,  the  other  overlying  the  glacials  and  considered 
as  of  “Permian”  age.  It  will  accordingly  be  instructive  to  describe 
in  some  detail  the  certain  sections  that  I  visited  at  the  foot  of  this 
great  range  some  25  km.  to  the  south  of  San  Juan,  where  the  relation¬ 
ship  of  the  plant-bearing  zone  to  the  glacials  is  beyond  all  question. 
The  area  examined  is  a  few  kilometers  long,  extending  from  a  point 
a  little  to  the  Rio  Grande  down  to  the  Rio  de  la  Mina,  as  shown  in  the 
sketch  map  (Fig.  2). 

The  Sierra  consists  of  a  lofty  barrier  of  gray-weathering  Ordo¬ 
vician  limestones  and  along  its  eastern  base  extends  a  group  of  highly 
tilted  green  slates  and  greywackes,  with  some  thin  fossiliferous  lime¬ 
stones,  presumably  of  Silurian  age.  The  Gondwana  beds  are  exposed 
in  the  foothills  and  in  a  number  of  small  ravines,  but  on  leaving  the 
slopes  their  outcrops  soon  become  hidden  beneath  deposits  of  boul¬ 
ders  and  gravels.  Good  exposures  are  found  of  the  basal  beds,  but  the 
outcrops  of  the  higher  groups  are  limited  and  sometimes  isolated. 
Piecing  together  the  various  sections,  which  can  be  done  without 
much  uncertainty,  there  is  discovered  a  thickness  of  about  360  meters 
of  the  Gondwana,  or,  as  they  have  customarily  been  termed,  ‘  ‘  Pagan- 
zo”  beds,  resting  unconformably  upon  the  Lower  Palaeozoic  and 
dipping  eastward  below  a  covering  of  tilted  Calchaquenos  (Tertiary) 
and  nearly  horizontal  Quaternary  gravels. 

The  Gondwana  embraces  three  distinct  glacial  horizons ,  one  of 
which  forms  the  very  base  of  the  system,  while  the  intercalated  sedi- 

17  Stappenbeck  (1910);  Keidel  (1922). 


ARGENTINA  AND  BOLIVIA 


29 


ments  between  that  and  the  second  horizon  yielded  plant  remains, 
among  which  were  the  Carboniferous  genera  Cardiopteris  and  Rha- 


Fig.  2 — Geological  sketch-map  of  a  small  area  along  the  eastern  base  of  the 
Sierra  Chica  de  Zonda  to  the  south  of  San  Juan.  OS,  Ordovician  and 
Silurian  limestones  and  shales.  1-7  Paganzo  system:  1,  first  glacial  zone; 
2,  plant-bearing  shales  and  sandstones;  3,  second  glacial  zone;  4,  sand¬ 
stones;  5,  third  glacial  zone;  6,  shales  with  some  sandstones;  7,  red  and 
dark  shales.  C,  Calchaquenos  and  Quaternary  gravels. 


copteris ,  but  no  marine  fossils.  The  discovery  of  these  forms,  taken  in 
conjunction  with  the  other  plants  found  in  this  locality  by  previous 
workers,  tends  to  invalidate  Keidel’s  argument  for  the  existence  of 


30  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

two  distinct  formations,  one  with  Carboniferous  plants  older  than 
the  Paganzo,  the  other  having  glacials  and  containing  the  Glossop- 
teris  flora.  For  this  reason  it  does  not  become  necessary  to  make  use 
of  the  two-fold  division  made  by  him  into  the  “Jejenes”  and  the 
“Zonda”  series,  nor  need  the  supposed  relationship  of  these  series  be 
argued.  In  only  this  respect  do  the  very  valuable  observations  and 
conclusions  of  Keidel  need  to  be  modified,  though  unfortunately  it 
will  affect  his  criticisms  of  the  writings  of  Bodenbender,  Hausen, 
Penck,  and  others. 

In  the  small  ravine  o.  5  km.  north  of  the  Rio  Grande  the  base  of  the 
Gondwana  is  excellently  exposed,  the  first  glacial  zone  (Plate  III,  B) 
from  8  to  20  meters  thick,  resting  upon  an  uneven  surface  of  highly 
tilted  slates  (A)  and  limestones  (B)  (Fig.  3).  At  the  point  X  the 
floor  is  actually  vertical,  and  in  the  pocket  below  it  lies  true  ground 


Fig.  3 — -Section,  about  75  meters  in  height,  in  ravine  north  of  the  Rio  Grande, 
Sierra  Chica  de  Zonda.  For  explanation,  see  text. 


moraine  (a),  above  which  comes  a  thin,  curving  layer  of  green  fissile 
shale  ( b )  with  annelid  or  crustacean  markings,  which  laps  over  the 
limestone  band  (B),  the  top  of  which  is  nevertheless  polished  and 
striated,  the  groovings  (Plate  IV,  A),  after  making  due  allowance  for 
the  subsequent  tilting,  being  directed  north-northwest- south- 
southeast.  The  overlying  glacials  (c)  range  from  a  true,  unbedded 
tillite  of  normal  character  to  a  stratified  fluvio-glacial  conglomerate 
having  the  inclusions  lying  with  their  longer  axes  parallel  to  the 
stratification,  though  striated  boulders  are  common.  They  pass  up 
into,  or  to  some  extent  are  even  interlaminated  with,  dark  carbon¬ 
aceous  shales  and  micaceous  flagstones  and  thin  sandstones  with 
occasional  plant  remains  (d),  grading  up  into  a  group  of  flagstones 
(e)  and  yellowish-gray  sandstones  (/),  sometimes  micaceous,  getting 
coarser  toward  the  summit,  the  succession  being  clearly  shown  in 
Plate  IV,  B. 

At  a  height  of  about  165  meters  above  the  base  the  second  glacial 
zone  makes  its  appearance  (Plate  V,  A).  In  the  neighboring  Rio  de 


ARGENTINA  AND  BOLIVIA 


31 


Jejenes,  on  the  southern  side  of  the  ravine  (Plate  V,  B) ,  its  base  is  sharp, 
the  band  incloses  lenses  of  sandy  stuff  as  shown  in  the  nearby  view 
(Plate  VI) ,  and  the  inclusions  are  as  a  rule  small  and  of  hard  rock, 
though  one  of  them,  composed  of  gneiss  and  resting  directly  upon 
the  sandstone,  constituting  the  floor,  is  nearly  3  meters  in  diameter. 
The  succession,  it  might  be  remarked,  is  a  perfectly  conformable  one. 
In  the  lower  ground  to  the  east,  where  this  zone  is  proceeding  to  dis¬ 
appear  beneath  higher  beds,  it  is  nearly  50  meters  thick,  composed 
of  a  lower  group  of  fliivio-glacial  sandstones  and  tills  and  a  thin  bed 
of  shale  above,  passing  up  through  boulder-shale  into  tillite  (Plate 
VII,  A) ;  finely  striated  erratics  can  readily  be  picked  up.  An  example 
has  been  figured  by  Coleman  and  it  is  hence  unnecessary  to  give  any 
additional  illustrations. 

The  top  passes  through  pebbly  grit  and  sandstone  into  greenish 
shaly  beds,  in  which  at  50  meters  there  appears  boulder-shale,  and 
next  the  third  glacial  zone,  about  12  meters  thick,  overlain  by  more 
hard,  greenish  shales,  and  these,  as  seen  to  the  south  in  the  channel  of 
the  Rio  de  la  Mina,  by  alternations  of  sandstone  and  shale,  with  a  thin 
zone  of  soft  black  carbonaceous  shales  constituting  the  highest  strata 
visible.  Although  so  thin,  this  upper  tillite  carries  some  exceptionally 
large  inclusions,  mainly  of  Ordovician  limestone,  one  slab  of  which, 
a  couple  of  meters  in  length,  contained  several  large  coiled  cephalo- 
pods.  The  conspicuous  green  coloring  in  some  of  the  beds,  absent 
in  the  region  to  the  northeast,  serves  to  link  this  formation  with 
the  equivalent  Pillahuinco  beds  of  the  Sierra  de  la  Ventana. 

In  this  terrain,  crossing  the  Rio  Grande  and  the  Agua  de  Jejenes, 
the  beds  are  dipping  regularly  eastward  and  are  not  dislocated, 
there  can  not  be  the  slightest  doubt  that  the  sequence  is  a  normal 
upward  one  which  is  resting  unconformably  upon  the  Silurian  and  is 
embracing  Paganzo  beds  only.  Great  weight,  therefore,  must  be 
attached  to  this  section,  since  it  provides  us  with  the  key  to  the 
Permo-Carboniferous  stratigraphy  of  a  very  wide  region  in  the  pre- 
Cordillera,  as  will  be  discussed  later  on. 

Proceeding  southward  in  the  direction  of  the  Rio  de  la  Mina, 
irregularities  make  their  appearance,  due  partly  to  the  fact  that  the 
floor  beneath  the  system  seems  to  have  been  highly  diversified,  and 
partly  to  subsequent  tectonic  movements,  by  which  anticlinal  cores 
of  Ordovician  limestone  have  been  driven  through  the  younger  for¬ 
mation.  By  such  movements,  what  from  their  lithological  peculiari¬ 
ties  must  be  regarded  as  slightly  higher  zones  of  the  Paganzo,  appear 
in  two  fine  continuous  domes  (Plate  VII,  B),  from  beneath  the  folded 
unconformable  Calchaquenos  formation  a  little  to  the  southwest  of 
the  lime-kilns  of  Carpinteria  not  far  from  the  Cerro  Bola,  a  group  of 
carbonaceous  and  micaceous  shales  with  nodules  carrying  plant 
remains,  soft  micaceous  sandstones,  and  reddish  mudstones  resting 


32  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

seemingly  through  the  medium  of  a  thrust-plane  upon  a  core  of  Ordo¬ 
vician  limestone ;  this  has  been  figured  very  roughly  by  Stappenbeck 
(1910,  p.  36,  Fig.  1). 

The  overshadowing  feature  of  the  sections  just  described  is  the 
direct  evidence  that  they  furnish  upon  the  position  of  the  plant¬ 
bearing  horizons  in  relation  to  the  glacials,  at  the  same  time  proving 
the  close  association  of  European  Carboniferous  plant  forms  with 
members  of  the  Glossopteris  flora,  thereby  bringing  the  succession 
into  harmony  with  the  sequences  observed  more  to  the  north  and 
northeast  in  the  Sierra  Umango,  Sierra  Villa  Union,  Sierra  de  los 
Llanos,  etc.,  namely,  near  the  base  of  the  Paganzo  system,  as  will  be 
discussed  later. 

Seemingly  the  glacials  are  represented  at  intervals  along  the  base 
or  flanks  of  this  range, .  as,  for  example,  in  the  Cuesta  de  Pedemal 
farther  to  the  south,  where  Stappenbeck38  reported  thick  conglomer¬ 
ates  overlain  by  beds  with  a  “Culm  flora”  resting  upon  the  Silurian; 
but  this  and  other  cases  require  to  be  reexamined  in  the  light  of  the 
sections  described  from  near  Rio  Grande. 

Working  southward  from  this  “type”  region,  mention  has  to  be 
made  of  the  fine  section  on  the  northwestern  side  of  the  Cerro  Pelado 
between  Mendoza  and  Uspallata,  where,  according  to  Stappenbeck 39 
the  Paganzo,  thrown  down  against  Ordovician  limestones  and 
dipping  southeastward  at  a  pretty  high  angle,  has  a  development  of 
basal  conglomerate,  stated  by  Keidel  to  be  glacial  in  its  nature,  rest¬ 
ing  on  presumed  Devonian  and  followed  by  conglomerates,  arkoses, 
sandstones,  shales,  bituminous  shales,  and  impure  coals  from  which 
Sigillaria ,  Annularia,  and  Gangamopteris  have  been  collected.  This 
section  is  of  further  interest  in  that  here  and  also  at  Villa  Vicenze 
toward  the  north  these  beds,  according  to  Keidel,40  are  overlain  with 
strong  unconformity  by  the  sediments  and  volcanics  of  the  upper 
Triassic. 

The  mention  by  Windhausen41  of  the  “Permian”  glacial  con¬ 
glomerate  resting  unconformably  on  older  beds  near  San  Rafael  to 
the  south  in  the  curious  Sierra  Pintada  with  its  northwest-southeast 
trend  is  important,  as  such  would  indicate  a  link  between  the  glacials 
of  the  Sierra  de  la  Ventana  and  those  of  the  Mendoza  district. 

In  the  museum  of  the  Geological  Survey  at  Buenos  Aires  stands 
a  photograph  of  an  exposure  of  a  tillite  labeled  “Arroyo  del  Chiquero, 
High  Cordillera,  Mendoza,”  which  apparently  refers  to  outcrops  at 
the  base  of  the  Sierra  de  Tigre,  some  40  km.  to  the  northwest  of 
Uspallata.  This  helps  to  connect  with  the  important  occurrence 
recorded  by  Keidel  at  Leoncito  Encima  in  the  same  valley  further  to 
the  north,  25  Ion.  distant  from  Barreal  and  with  that  at  the  Quebrada 


38  Stappenbeck  (1910),  p.  36. 

39  Stappenbeck  (1910),  p.  51  and  Fig.  2. 


40  Verbal  communication. 

41  Windhausen  (1918),  p.  35. 


ARGENTINA  AND  BOLIVIA 


33 


del  Salto  immediately  to  the  east  of  the  latter  village,  referred  to  by 
Stappenbeck,42  though  he  did  not  then  realize  the  glacial  character  of 
the  basement  conglomerate.  Compared  with  the  succession  in  the 
Sierra  Chica  de  Zonda  these  two  occurrences  are  outstanding,  because 
the  presence  of  marine  fossils  in  them  indicates  that  within  a  length 
of  45  km.,  though  appreciably  greater  distance  when  the  effect  of 
folding  has  been  allowed  for,  the  formation  has  changed  in  character 
from  continental  to  marine ;  it  has  now  been  termed  the  Tontal  series. 

In  the  Arroyo  de  Cabeceras,  about  3  km.  above  the  homestead  of 
Leoncito  Encima,  I  discovered  the  tillite  folded  in  with  the  pre- 


Fig.  4 — An  infolded  patch  (stippled)  of  tillite  in  Palaeozoic  beds  close  to 

Leoncito  Encima,  Barreal. 


sumed  Devonian  slates  and  greywackes  in  an  extraordinary  fashion, 
as  showm  in  Figure  4,  a  feature  due  to  the  superposition  of  the  pre¬ 
vailing  north-south  crumplings  of  the  pre-Cordillera  upon  a  pre¬ 
sumably  older  northwest-southeast  folding.  The  base  of  the  tillite 
transgresses  across  the  strike  of  the  supporting  Palaeozoics  and  the 
unconformable  contact  can  clearly  be  made  out  at  several  points, 
where  the  surface  below,  when  visible,  is  polished  and  shows  striae 
directed  north-northwest-south-southeast  (making  allowance  for 
the  considerable  subsequent  tilting  of  the  floor)  and  which  are  not 
strictly  parallel,  as  in  slickensided  faces,  but  cross  one  another  at  a 
very  acute  angle  in  the  manner  characteristic  of  glacial  pavements. 
The  tillite  is  dark  green,  fine-grained,  with  small  inclusions,  rarely 
more  than  15  cm.  in  diameter,  many  of  them  being  finely  striated; 


42  Stappenbeck  (1910),  p.  46. 


34  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

i 

a  rude  bedding  is  present  in  places,  brought  out  by  some  banded  and 
more  quartzitic  layers.  The  thickness  preserved  in  this  narrow  ravine 
would  not  be  more  than  about  30  meters. 

About  150  meters  distant  from  the  homestead  of  Leoncito  Encima 
is  the  outlier  mentioned  by  Keidel.43  Lack  of  time  unfortunately 
prevented  any  detailed  examination  of  either  the  base  or  the  topmost 
beds,  but  some  sandstones  and  thin  shales  were  observed  overlain  by 
tillite,  and  the  latter  in  turn  by  gritty  sandstone  with  pebbles,  fol¬ 
lowed  by  fluvio-glacial  cong^merates.  Important  was  the  presence 
of  some  particularly  fine  “boulder  pavements”  of  the  kind  recorded 
in  the  Sierra  de  la  Vent  ana,  with  erratics  exposed  on  the  curving, 
ploughed-up  surfaces,  showing  good  striae  directed  north-northwest 
and  therefore  in  full  agreement  with  the  evidence  obtained  higher  up 
the  valley,  as  well  as  in  the  Sierra  Chica  de  Zonda.  Fossils  were 
collected  here  by  Keidel  either  as  casts  or  in  nodules  of  clayey  lime¬ 
stone,  principally  of  brachiopods  such  as  Spirifer,  Dielasma,  etc.,  but 
not  specifically  determined  by  him,  though  he  has  noted  forms  resem¬ 
bling  Spirifer  alatus  and  S.  rugulatus,  suggestive  of  the  Permian;44 
Productus  was  absent.  Whether  these  beds  at  Leoncito  Encima  are 
really  Permian,  as  supposed  by  Keidel,  or  Carboniferous  like  those  at 
Barreal,  to  be  described  below,  can  only  be  decided  by  the  working 
out  of  these  fossils. 

I  was  unable  to  trace  the  glacials  continuously  northward,  but 
feel  fairly  confident  that  it  must  be  the  same  formation  that  is  laid 
bare  immediately  to  the  east  of  Barreal,  in  the  Quebrada  del  Salto, 
the  beds  being  finely  sectioned  by  a  small  ravine  a  kilometer  to  the 
south  of  the  latter,  this  dry  watercourse  rising  in  an  anticlinal  valley 
scooped  out  of  shales  overlying  the  tillite  and  hemmed  in  by  a  ring 
of  hard  gray  and  speckled  quartzitic  sandstones,  thin-bedded  red 
flagstones,  gray  and  bluish  siliceous  shales,  and  some  soft  dark  shales 
(Plate  VIII,  A).  The  tillite  is  greenish  and  homogeneous,  passing  by 
degrees  through  sandy  mudstones  into  olive  shales  with  occasional 
small  pebbles,  and  from  these  into  olive  sandy  shales  without  inclu¬ 
sions.  Not  more  than  25  meters  of  glacial  material  was  exposed  at 
this  spot,  with  the  base  not  visible,  though  not  improbably  a  search 
to  the  south  would  disclose  its  floor. 

Fossils  occur  not  only  in  the  overlying  shales  in  profusion,  but 
less  abundantly  in  the  mudstones  with  erratics,  though  absent  from 
the  tillite  proper.  Spirifer ,  Productus ,  Pseudamusium ,  and  Spiriferina 
are  common,  while  Polypora  and  Fenestella  are  conspicuous  low  down 
in  the  mudstones,  thus  duplicating  the  features  seen  in  the  lower 
marine  series  of  the  Hunter  River  region  of  New  South  Wales,  with 
its  glacial  erratics  and  abundant  polyzoa. 

Some  150  to  200  meters  above  this  fossiliferous  zone,  exposed 

43  Keidel  (1922),  p.  256.  44  p.  334. 


ARGENTINA  AND  BOLIVIA 


35 


close  by  and  just  to  the  north  in  the  Quebrada  del  Salto,  is  another 
horizon  of  dark,  reddish  weathering,  sandy  shales  from  which  numer¬ 
ous  mollusca  were  collected ;  this  must  be  the  locality  discovered  by 
Stappenbeck,45  from  which  he  obtained  a  fauna  with  Spirifer  supra- 
mosquensis  Nik.,  etc,  correctly  regarded  by  him  as  of  upper  Carbon¬ 
iferous  age.  Some  higher  beds  of  hard  sandstones  and  shales  follow, 
covered  up  by  Calchaquenos  to  the  north,  while  on  the  east  the  suc¬ 
cession  ends  by  faulting  against  “Rhaetic”  beds. 

The  forms  collected  from  these  two  horizons  are  fully  discussed 
by  Dr.  Cowper  Reed  in  the  Appendix,  and  it  will  suffice  therefore  to 
quote  his  important  decision  that  these  Barreal  faunas  can  without 
hesitation  be  ascribed  to  the  Carboniferous  and  probably  to  the  base 
of  the  upper  Carboniferous.  The  tillite  should  belong,  then,  to  about 
the  border-line  between  the  Moscovian  and  theUralian,  that  is  to  say, 
between  the  Westphalian  and  the  Stephanian,  wherefore  it  has  to  be 
concluded  that  this  succession  near  Barreal  must  be  the  marine 
equivalent  of  the  glacials  with  their  plant-bearing  zone  of  the  Paganzo 
system  of  the  Sierra  Chica  de  Zonda.  Phases  transitional  between 
them  will  now  have  to  be  sought  for  in  the  intermediate  belts  of 
Paganzo  mapped  by  Stappenbeck 46  in  the  Sierra  Alta  de  Zonda  and 
on  the  western  side  of  the  Paramillo  de  Tontal,  where,  as  recorded  by 
him,  conglomerates,  arkose,  green  and  reddish  slates,  and  sandstones 
rest  on  “Devonian”  greywackes. 

Further  to  the  north  towards  Jachal,  illuminating  sections  have 
been  recorded  by  Stappenbeck  and  in  more  detail  by  Keidel.47  For 
example,  fluvio-glacial  beds  are  mentioned  by  the  latter  as  resting 
with  slight  discordance  upon  a  thick  group  of  unfossiliferous  though 
post-Devonian  greywackes  in  the  Quebrada  de  Talacasto  (lat.  310). 
In  the  Lomas  de  los  Piojos,  a  little  to  the  south  of  Jachal,  reposing 
unconformably  on  the  lower  Devonian  with  Leptocoelia  flabellites  or 
on  upper  Silurian  beds,  is  a  tillite  passing  up  into  fluvio-glacial  con¬ 
glomerates  and  these  into  sandstones  with  occasional  boulders,  the 
whole  possessing  a  thickness  of  from  50  to  60  meters.  At  one  spot 
Keidel48  found  the  morainic  matter  resting  upon  a  well-striated 
pavement  of  fossiliferous  Devonian  sandstones  with  the  groov¬ 
ings  directed  northwest-southeast  (see  his  Plate  VII,  Fig.  2). 

Evidence  of  glacial  deposits  is  forthcoming  from  the  Cerro  Fuerte, 
to  the  east  of  Jachal,  and  also  from  farther  north,  near  Guandacol, 
similar  strata  cropping  out  around  the  southern  end  of  the  Cerro 
Villa  Union  and  the  Sierra  de  Umango,  being  well  seen,  for  example, 
on  the  western  side  of  the  Cerro  Guandacol,  as  described  by  Boden- 
bender  and  Hausen,49  the  latter  recording  a  coarse,  tillite-like  con- 


45  Stappenbeck  (1910),  p.  37. 
*6Ibid.,  p.  43. 

47 Keidel  (1921). 


isIbid.,  p.  59. 

49  Hausen  (1921),  p.  70. 


36  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

* 

glomerate  at  the  base,  followed,  but  overlapped,  by  sandstones  and 
shales  and  by  much  younger  stages  of  the  Paganzo,  including  beds  of 
Rhaetic  age.  More  detailed  reference  to  these  last  and  to  their  equiv¬ 
alents  in  the  ranges  more  to  the  east,  e.g.,  the  Sierra  de  Sahogasta, 
Sierra  del  Valle  Fertil,  and  Nevada  de  Famatina,  will  be  made  later. 
Undoubted  glacials  have  not  yet  been  recorded  to  the  east  and  north¬ 
east  of  the  last  named,  barring  Penck’s  assertion  of  an  unbedded 
tillite-like  formation  close  to  Angulos  on  the  eastern  side  of  the  chain. 
Instructive  is  his  discovery  in  the  Puna  de  Atacama  of  Cardiopteris 
polymorpha  in  coaly  shales  resting  on  the  conglomeratic  sandstones  of 
the  lowest  division  of  the  Paganzo,  as  in  San  Juan,  while  intercalated 
basaltic  flows  are  also  present. 

(2)  The  Plant-bearing  Beds  and  Their  Age 

Though  this  discussion  might  more  appropriately  follow  the 
succeeding  account  of  the  Paganzo  system,  it  is  most  conveniently 
introduced  here  in  order  to  demonstrate  the  close  relation  of  the 
fossiliferous  bands  to  the  glacial  horizons  of  the  Sierra  Chica  de 
Zonda. 

In  the  course  of  a  brief  search  in  the  Rio  Grande  I  obtained  from 
the  carbonaceous  shales  (dt  Fig.  3)  between  the  first  and  second 
glacial  horizon  and  about  50  meters  above  the  base  of  the  system, 
specimens  of  Cardiopteris  polymorpha  and  Rhacopteris  szajnochai , 
while  Bodenbender 50  collected  (almost  certainly  from  this  band, 
which  is  to  be  found  cropping  out  again  in  the  next  ravine  nearby, 
that  of  the  Arroyo  de  Jejenes)  Rhacopteris  szajnochai ,  and  in  addition 
Gangamopteris  cyclopteroides ,  Glossopteris  browniana,  Cordaites ,  species 
of  Sphenopteris ,  and  fragments  of  a  fish,  Rhadinichthys  argentinus 
Tornq.  So  far  as  I  can  make  out,  just  a  little  to  the  north  of  the  Rio 
Grande  and  west  of  Paradero  kilometer  489  is  Rinconada,  whence 
Bodenbender  gathered  Cardiopteris  polymorpha ,  Adiantites  antiquus , 
Neuropteridium  validum ,  and  species  of  Sphenopteris .  Some  5  km. 
south  of  Jejenes  and  to  the  west  of  Carpinterla  he  also  discovered 
Glossopteris  ampla ,  presumably  in  the  same  beds  as  Bergiopteris 
insignis ,  Lepidodendron  cf.  australe,  and  Asterocalamites  scrobiculatus , 
while  beyond  at  Retamito,  in  the  Quebrada  del  Agua,  in  beds  over- 
lying  thick  conglomerates — not  improbably  glacials — resting  upon 
the  Silurian,  Bodenbender  found  Rhacopteris  sp.,  Botrychiopsis 
weissiana ,  Asterocalamites  scrobiculatus ,  Lepidodendron  pedroanum, 
L.  australe ,  L.  cf.  notlium ,  and  Cordaites  sp.  Kurtz 51  has  described 
several  other  forms  from  these  several  localities,  such  as  Rhacopteris 
inequilatera ,  var.  ovata,  Archceopteris  argentine ,  and  Cardiopteris 
elegans. 

60 Bodenbender  (1902),  p.  203,  (1911),  p.  86;  Stappenbeck  (1910),  p.  40. 

61  Kurtz  (1921-22). 


ARGENTINA  AND  BOLIVIA 


37 


More  to  the  south,  in  bituminous  shales  above  the  glacials  of  the 
Cerro  Pelado,  Gangamopteris  is  associated  with  Sigillaria  and  Aster o- 
calamites.  Traveling  northward,  one  finds  at  Trapiche,62  between 
Jachal  and  Guandacol,  Cardiopteris  polymorpha,  with  Lepidodendron 
(. Lepidophloios )  laricinus ,  Cordaites  hislopi,  and  Neuropteridium 
validum,  the  latter  also  at  Cerro  Bola,  a  little  to  the  east,  and  at  Sano- 
gasta,  while  in  the  Cuesta  Colorada  (Escala  de  Famatina)  Rhacop- 
teris  inequilatera  has  been  gathered.  Penck 53  has  reported  the  finding 
in  the  Puerta  de  Guanchin  in  the  Puna  de  Atacama,  of  Cardiopteris 
polymorpha ,  Botrychiopsis  weissiana,  Phyllotheca  australis ,  and 
Gingkophyllum  grasseti  in  clay  shales  and  thin  impure  coals  overlying 
the  basal  conglomerate,  here  22  meters  thick.  In  the  Sierra  de  Vilgo 
at  the  Cuesta  de  la  Torre,  Lepidodendron  aculeatum  occurs  low  down 
in  stage  I  of  the  Paganzo.  At  Saladillo,54  near  the  southern  end  of 
the  Sierra  del  Velasco,  black  shales  have  yielded  Lepidodendron  selagi- 
noides  and  L.  veltheimianum .  On  the  other  hand,  proceeding  south¬ 
eastward  into  the  Sierra  de  los  Llanos,  we  have  recorded  from  the 
Arroyo  Totoral  and  elsewhere  Neuropteridium  validum,  Cordaites 
hislopi ,  Glossopteris  retifera,  G.  indica ,  Phyllotheca  deliquescens ,  and 
other  forms,  while  at  Bajo  de  Velis,55  in  the  Sierra  de  San  Luis  farther 
to  the  south,  has  been  obtained  the  well-known  assemblage  including 
Neuropteridium  validum ,  Gangamopteris  cyclopteroides ,  Cordaites 
hislopi,  Noeggerathiopsis  whittiana,  Rhipidopsis  densinervis,  R. 
ginkgoides,  etc. 

Keidel 56  has  been  to  great  pains  in  order  to  prove  that  there  are 
actually  two  distinct  series  resting  unconformably  upon  the  older 
Palaeozoics,  one  with  a  flora  including  lower  and  upper  Carboniferous 
forms  and  hence  of  Carboniferous  age,  overlain  by  the  second  formed 
of  the  glacials  and  the  sediments  with  the  Glossopteris  flora,  belong¬ 
ing  to  the  Gondwana  system  and  of  “Permian”  age. 

It  must  candidly  be  admitted  that  the  evidence  as  to  the  precise 
horizons  from  which  these  several  identified  collections  were  made  is 
not  beyond  criticism,  and  unfortunately  my  limited  opportunity  for 
collecting  did  not  enable  me  to  dispel  such  doubts,  though  the  ques¬ 
tion  could  very  readily  be  settled.  It  can  nevertheless  be  affirmed 
that  along  both  the  Rio  Grande  and  the  Arroyo  de  Jejenes  the  car¬ 
bonaceous  shales  (d,  Fig.  3)  constitute  a  zone  such  as  would  natur¬ 
ally  be  searched  by  the  collector,  although  not  the  only  fossiliferous 
horizon  present,  since  the  upper  part  of  the  sandstone  group,  /,  also 
yielded  some  poorly  striated  stems.  No  plants  were  observed  in  the 
sandstones  between  the  second  and  third  glacial  zones  and,  sugges¬ 
tively,  no  strata  higher  than  the  latter  are  represented  in  those  two 


52 Bodenbender  (1911),  pp.  82-83. 
63  Penck  (1920),  p.  146. 

M  Bodenbender  (1911),  p.  81. 


65  Kurtz  (1895). 
60  Keidel  (1922). 


38  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

localities.  To  the  south,  however,  along  the  Rio  de  la  Mina,  plant 
fragments  were  noticed  in  shaly  sandstones  between  30  and  40  meters 
above  the  third  glacial  zone. 

It  would  consequently  seem  most  likely  that  Bodenbender’s 
specimens  mentioned  above  from  the  Arroyo  de  Jejenes  came  from 
the  strata  lying  between  the  first  and  second  glacial  zones.  Boden- 
bender,  Kurtz,  and  others  nowhere  remark  that  the  plants  collected 
by  them  in  any  one  locality  near  the  base  of  the  Sierra  Chica  de 
Zonda  were  actually  derived  from  distinct  horizons,  wherefore,  until 
more  careful  collecting  has  been  carried  out,  we  can  only  assume  that 
each  lot  was  obtained  from  some  stratigraphical  unit  rather  than 
from  several  horizons  a  good  distance  apart. 

In  analyzing  these  various  collections,  we  observe  further  that  in 
one  locality  or  another  some  typical  member  of  the  “northern  flora’ ’ 
is  in  apparent  association  with  some  member  of  the  “southern,  ”  and 
this  in  so  many  ways  that  we  have  difficulty  in  escaping  from  the 
conclusion  that  all  these  various  plants  must  probably  have  occurred 
intermingled  on  horizons  intimately  associated  with  the  glacial 
series.  It  will,  however,  not  be  denied  that  the  southern  forms  might 
perhaps  have  come  from  slightly  higher  levels  within  that  particular 
series  than  those  that  yielded  the  northern  elements,  and  it  will 
therefore  be  conceded  that  Gangamopteris ,  Glossopteris,  etc.,  if  not 
actually  accompanying  Rhacopteris,  Cardiopteris ,  etc.,  must  occur 
shortly  above  this  lowest  plant-bearing  carbonaceous  zone  d ,  with 
its  northern  Carboniferous  flora.  A  search  should  enable  this  highly 
important  palaeobotanical  relationship  to  be  definitely  established. 

Granted  that  the  data  have  been  correctly  interpreted,  the  pres¬ 
ence  of  Gangamopteris,  Glossopteris ,  Neuropteridium,  etc.,  would 
suggest  that  the  whole  of  this  definitely  conformable  succession, 
down  to  its  very  base,  resting  discordantly  upon  pre-Carboniferous 
strata,  should  be  regarded  as  forming  part  and  parcel  of  the  Gond- 
wana  system.  In  this  conclusion  I  find  myself  in  accord  with  Boden- 
bender,  Stappenbeck,  and  Penck.  The  sections  on  the  Rfo  Grande 
and  Arroyo  de  Jejenes  are  particularly  clear,  and,  while  some  uncer¬ 
tainty  attaches  to  the  precise  levels  from  which  many  of  the  plants 
have  been  collected,  the  interpretation  here  advanced  does  not  seem 
to  me  to  do  violence  to  the  facts. 

It  is  most  suggestive  that  in  the  chain  of  outcrops  from  the  Cerro 
Pelado  due  northward  to  the  Puna  de  Atacama  and  eastward  into 
Famatina,  the  bulk  of  the  plants  appear  to  have  been  found  in  a  zone 
of  carbonaceous  shales  with  occasional  thin  layers  of  impure  coal 
that  lies  not  far  above  the  basal  conglomerates  and  arkoses,  beds 
largely  of  glacial  origin.  From  the  section  in  the  Sierra  Chica  de 
Zonda  it  is  clear  that  this  zone  (d,  Fig.  3)  is  overlain  by  glacials  as 
well,  but  how  far  the  latter  extend  northward  is  a  matter  for  future 


ARGENTINA  AND  BOLIVIA 


39 


investigation.  It  is  precisely,  too,  in  this  western  section  of  Argen¬ 
tina,  that  the  northern  plant  forms  with  a  Carboniferous  aspect 
are  to  be  found,  and  they  most  decidedly  indicate  an  age  for  the 
inclosing  strata  not  younger  than  upper  Carboniferous  ( Stephanian  or 
Pennsylvanian) ,  possibly  even  the  top  of  the  middle  Carboniferous. 

On  the  other  hand,  Bodenbender 57  is  quite  definite  that  in  the 
region  eastward,  Sierra  de  Velasco,  Sierra  de  los  Llanos,  etc.,  the 
plant-bearing  beds  are  of  similar  lithological  character  and  are  all 
more  or  less  on  the  same  particular  horizon,  within  Stage  I,  seemingly 
in  its  upper  half,  and  hence  apparently  on  a  slightly  higher  level  than 
in  the  west.  It  is  significant  too,  that  in  the  east  the  records  of 
northern  plant  forms  all  but  fail,  but  that  Lepidodendron  aculeatum 
occurs  in  the  Cerro  de  Vilgo  lower  down  than  is  usual,  while  near 
Cerro  Bola  in  the  west  Cordaites  hislopi  and  Neuropteridium  validum 
are  represented  near  the  top  of  the  group.  Taken  in  conjunction 
with  the  fact  that  some  carbonaceous  shales  also  occur  in  the  Sierra 
Chica  de  Zonda  some  distance  above  the  third  glacial  horizon,  there 
is  a  definitely  proved  stratigraphical  overlapping  toward  the  east 
(referred  to  below) ,  causing  higher  zones  to  come  to  rest  on  the  ancient 
rocks,  it  would  seem  that  in  the  west  lower  horizons  may  generally  be 
represented,  which  tend  to  be  missing  in  the  east.  This  view  is  sup¬ 
ported  by  the  triple  development  of  the  glacials  in  the  west  and  their 
absence,  or  perhaps  their  non-record,  in  the  east.  The  first  mentioned 
condition  is  certainly  the  case  at  Bajo  de  Velis,  where  I  was  able 
to  examine  the  base  of  the  Paganzo,  for  the  beds  with  Gangam - 
opteris  rest  directly  on  schists  without  the  intervention  of  a  glacial 
conglomerate. 

Some  remarks  are  needed  regarding  the  plants  themselves  as 
indicators  of  age.  The  determinations  were  all  made  by  Kurtz,58  and 
in  a  number  of  cases  no  descriptions  were  published,  though  recently 
a  few  have  posthumously  appeared,59  in  most  cases,  however,  unac¬ 
companied  by  figures.  I  consequently  have  found  it  difficult  to 
criticize  the  determinations,  while,  when  in  Cordoba,  I  had  only  time 
to  examine  the  extensive  collection  of  Rhastic  plants  in  the  museum 
of  the  university. 

It  might  be  remarked  at  the  outset  that  the  majority  of  the  mem¬ 
bers  of  the  Glossopteris  flora  are  of  little  or  no  value  in  establishing  the 
absolute  age  of  the  beds.  Recent  work  has  been  showing  more  and 
more  that  certain  genera  and  species  thereof  had  a  long  range  in 
time  and  these  sections  in  Argentina  are  of  immense  importance, 
therefore,  in  demonstrating  that  Gangamopteris  cyclopteroides ,  Glos¬ 
sopteris  browniana,  and  Cordaites  hislopi  extend  back  well  into  the 
Carboniferous,  as  also  appears  to  be  the  case  in  New  South  Wales. 


67 Bodenbender  (i9ii),p.  83. 

68  Kurtz  (18950);  Bodenbender  (1904),  (191 1). 


69  Kurtz  (1921-22). 


40  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

Of  the  undoubted  “northern”  forms,  Asterocalamites  scrobicu- 
latus  (Schloth),  described  originally  in  1894-95  by  Kurtz  as  Archx- 
ocalamites  radiatus ,  is  found  in  Europe  and  North  America,  being 
sometimes  known  as  Bornia  scrobiculata  Stern,  extending  up  into 
the  lower  part  of  the  upper  Carboniferous  (Pennsylvanian) ,  but  has 
been  recorded  by  Walkom  under  the  name  of  Archxocalamites  scro- 
biculatus  from  Queensland,  together  with  Glossopteris  and  Cordaites, 
the  only  other  country  in  which  this  remarkable  association  has  yet 
been  recorded.  Adiantites  is  a  genus  with  a  similar  range,  but  from 
Kurtz’s  meager  description  thereof  and  the  absence  of  a  figure,  direct 
comparison  with  the  Culm  species  A .  antiquus  (Ett)  is  not  possible. 
Archxopteris  argentinx  Kurtz  is  compared  by  him  with  A .  wilkinsoni 
Feist,  from  New  South  Wales,  while  with  Archxopteris  obtusa  Lesq., 
from  the  Pennsylvanian,  Kurtz  compares  his  Bergiopteris  insignis. 
Botrychiopsis  weissiana  Kurtz,  with  Cardiopteris- like  pinnules, 
appears  to  be  intermediate  between  Cardiopteris  and  Neuropteris. 

Cardiopteris  polymorpha  (Goepp)  is  a  lower  Carboniferous  form 
and  does  not  seem  to  be  known  from  the  upper  division ;  an  undeter¬ 
mined  species  comes  from  the  Kuttung  series  (middle  Carboniferous) 
of  New  South  Wales.  C.  elegans  Kurtz  stands  close  to  C.  polymorpha . 
Rhacopteris  inequilatera  (Goepp)  has  been  referred  by  Dun  to 
Aneimites  ( Otopteris )  ovata  (McCoy),  with  which  Kurtz  has  placed 
R.  inequilatera  var.  ovata  from  Jejenes,  including  also  A.  austrina 
Eth.,  the  last  from  the  Drummond  series  of  Queensland,  the  first 
named  from  the  Kuttung  series  of  New  South  Wales,  which  contains 
other  species  of  Rhacopteris.  Lepidodendron  veltheimianum  is  a  lower 
Carboniferous  species,  while  L.  pedroanum  occurs  in  the  Bonito  group 
of  Brazil.  The  Sphenopterids  may  be  upper  Carboniferous  forms, 
but  only  one  has  been  figured.60 

It  might  be  remarked  that  the  only  records  of  such  Palaeozoic 
plants  are  from  Lake  Titicaca  in  Bolivia  and  from  Paracas  on  the 
coast  of  Peru  by  Seward  61  and  Berry.62  No  specific  names  are  given 
by  the  former,  but  his  Sphenopteris  sp.  recalls,  however,  S.  boden- 
benderi  Kurtz,  but  appears  to  agree  better  with  the  description  given 
of  S.  fonsecx  Kurtz,  from  Carpinteria,  though  no  figure  of  the  latter 
has  been  published.  Berry,  however,  has  identified  among  others 
Lepidodendron  rimosum  Stem,  L.  obovatum  Stern,  Catamites  suckowii 
Brong.,  Eremopteris  whitei  Berry,  and  E.  peruiana  Berry.  He  regards 
the  flora  as  probably  Westphalian  (middle  Carboniferous)  and  points 
out  that  on  Lake  Titicaca  at  least  one  of  these  forms  occurs  in  strata 
underlying  the  marine  upper  Carboniferous  (Uralian). 

In  spite  of  some  uncertainties  in  the  identifications  and  the 
necessity  of  revision,  there  can  be  no  doubt  that  the  northern  ele- 

60  Kurtz  (1921-22),  PI.  XIV,  Nos.  138,  138a,  and  139.  62  Berry  (1922). 

61  Seward  (1922). 


ARGENTINA  AND  BOLIVIA 


41 


ments  in  this  western  Argentine  flora  definitely  place  it  on  about  the 
border  line  of  the  middle  and  upper  Carboniferous.  So  far  back  as  1895 
Kurtz  correctly  pointed  out  this  fact  and  also  drew  attention  to  the 
parallelism  with  the  plant-bearing  Carboniferous  beds  of  New 
South  Wales  and  Queensland.  The  discovery  of  associated  glacials 
both  in  San  Juan  and  in  the  Seaham  area  of  New  South  Wales 
strengthens  this  comparison  enormously.  The  floras  of  the  lowermost 
Paganzo  and  of  the  Kuttung 63  series  of  New  South  Wales  have  strong 
resemblances,  and  in  each  case,  and  also  in  Peru,  there  is  the  com¬ 
plete  absence  of  species  of  the  common  Neuropteris ,  Pecopteris,  and 
Alethopteris  groups,  all  of  which  become  very  abundant  in  the  typical 
middle  and  upper  Carboniferous  floras  in  various  parts  of  the  world. 
The  presence  of  the  Glossopteris  flora  and  its  absence  from  the  Kut¬ 
tung,  so  far  as  we  know,  suggest  an  age  slightly  younger  than  that 
of  the  latter  for  the  lowermost  beds  in  Argentina,  which  would 
place  them  at  about  the  beginning  of  the  upper  Carboniferous 
(Pennsylvanian) . 

The  flora  of  the  beds  situated  to  the  east  of  San  Juan,  with  its 
paucity  of  Northern  forms,  can  be  compared  with  that  of  the  lower 
marine  series  of  New  South  Wales  that  immediately  follow  the 
Kuttung,  or  the  Queensland  ‘  ‘  Permo-Carboniferous  ’  ’  with  species  of 
Glossopteris,  Sphenophyllum,  Cordaites,  and  Sphenopteris.  Just  as  in 
the  Hunter  River  area  glacial  conditions  recurred,  so  was  the  case  in 
San  Juan,  where  the  basal  glacials  and  lowermost  plant-bearing 
group  were  succeeded  by  more  morainic  matter,  all,  however,  still  of 
Carboniferous  age. 

This  strong  parallel  between  Argentina  and  the  eastern  side  of 
Australia  must  be  emphasized,  since  under  the  displacement  hy¬ 
pothesis  the  space  separating  these  two  regions  would  at  this  epoch 
have  been  enormously  less.  This  question  wx>uld,  consequently, 
appear  to  be  worthy  of  examination  from  other  viewpoints  in  the 
light  of  this  hypothesis. 

(3)  The  Name  “Paganzo  System” 

Thus  far  attention  has  been  focussed  almost  wholly  upon  the 
basal  portion  of  the  system  as  developed  in  that  section  of  the  pre- 
Cordillera  from  Mendoza  northward  into  La  Rioja  with  the  object, 
firstly,  of  bringing  out  the  evidence  for  the  existence  of  glacial 
deposits,  as  in  other  parts  of  Gondwanaland,  and,  secondly,  of  show¬ 
ing  that  certain  of  the  scattered  florules  are  actually  sandwiched 
between  glacial  horizons.  Before  reviewing  the  information  available 
regarding  these  and  the  still  higher  strata  that  are  so  extensively 
developed  in  the  region  to  the  east  and  northeast — not  only  in  the 
pre-Cordillera,  but  in  the  central  or  Pampean  ranges  as  well — some 

63  Siissmilch  and  David  (1920). 


42  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

discussion  becomes  necessary  upon  the  limits  to  be  set  to  the 
“Paganzo  beds.  ” 

This  name  was  given  by  Bodenbender 64  from  the  village  of  Pagan - 
zo  to  the  south-southwest  of  La  Rioja,  where  the  several  stages  or 
divisions  of  this  important  group  of  strata  are  so  well  developed,  but 
from  which  the  so-called  “Rhastic  ”  beds  were  definitely  excluded.  It 
is  true  that  Keidel65  subsequently  adopted  a  new  classification,  the 
‘  ‘  La  Rioja  system,  ”  a  course  in  which  he  was  doubtless  influenced  by 
his  separation  of  the  basement  strata  in  San  Juan  into  the  two  series 
of  “  Jejenes  ”  and  “Zonda.  ”  Now  that  it  has  been  shown  that  such  a 
division  is  scarcely  necessary,  the  term  “La  Rioja  system”  becomes 
superfluous  and  there  would  be  no  genuine  grounds  for  superseding 
the  original  and  well-established  term  “Paganzo,  ”  which  has  so  firm 
a  place  in  geological  literature.  On  the  other  hand,  the  exclusion  of 
the  “Rhaetic”  from  the  Paganzo  is  wholly  indefensible,  since,  (a) 
these  younger  beds  generally  include  some  strata  of  upper  Triassic 
age  similar  in  many  ways  to  the  older  groups  of  the  Gondwana;  ( b ) 
they  are  non-marine  in  character;  (c)  although  they  are  generally 
unconformable  to  the  lower  stages  of  the  Paganzo,  places  are  known 
where  no  marked  break  has  yet  been  recorded,  or  where  as  yet  no 
inferior  limits  can  be  set  to  the  group ;  and  (d)  they  admittedly  cor¬ 
respond  with  the  upper  part  of  the  Santa  Catherina  system  of  Brazil, 
with  the  Stormberg  series  of  South  Africa  and  with  a  part  of  the 
middle  Gondwana  of  the  type  region  of  India. 

As  will  be  realized  from  the  study  of  the  following  pages,  it  would 
be  difficult  to  make  out  any  adequate  case  for  the  exclusion  of  these 
younger  beds,  excepting  for  their  general  unconformable  position, 
which  relationship,  it  must  be  pointed  out,  is  certainly  present  some¬ 
where  in  each  of  the  other  sections  of  Gondwanaland.  Since  the 
strata  thus  embraced  range  from  Carboniferous  to  Rhaetic  in  age,  it 
is  furthermore  clear  that  a  mere  “series”  would  be  insufficient  to 
include  them — nothing  less,  indeed,  than  a  “system,”  so  the  Paganzo 
must  be  given  a  rank  equal  to  the  systems  of  the  Santa  Catherina, 
Karroo,  or  Gondwana,  of  which  it  is  the  Argentine  representative. 

In  the  following  pages,  therefore,  though  contrary  to  practice  in 
Argentina,  the  so-called  “ Rhaetic ”  will  he  regarded  as  forming  the 
uppermost  member ,  i.e.y  Stage  IV >  of  the  Paganzo  system. 

(4)  The  Distribution  of  the  Paganzo 

Deposited  unconformably  upon  Palaeozoic  and  crystalline  rocks, 
and  largely  covered  by  Cretaceous  and  Tertiaries,  these  beds 
have  been  involved  in  the  Andine  movements,  wherefore  dips  are 
often  high,  inversion  may  occur,  while  faulting  and  thrusting  are 
common.  In  consequence,  the  beds  now  make  their  appearance  along 

65  Keidel  (1922),  p.  267. 


64  Bodenbender  (1911),  p.  47. 


ARGENTINA  AND  BOLIVIA 


43 


the  flanks  of  the  various  ranges,  occupying  a  position  intermediate 
between  their  Palaeozoic  or  crystalline  cores  (which  generally  compose 
the  mountain  mass)  and  the  Cretaceo-Tertiary  (which  commonly 
form  the  lower  ground) ,  and  therefore  crop  out  most  usually  in  the 
form  of  narrow  belts,  not  infrequently  obscured  over  considerable 
stretches  by  late  Tertiary  beds  or  by  Quaternary  gravels  and  sands. 
The  clarity  of  the  exposures,  due  to  the  broken  nature  of  the  ground 
and  the  aridity  of  these  regions,  is  consequently  offset  by  the  fre¬ 
quency  with  which  the  strata  are  hidden  by  these  younger  formations ; 
rarely  is  any  wide  area  to  be  found  occupied  by  the  Paganzo,  though 
the  system  doubtless  underlies  many  of  the  Tertiary-filled  valleys 
or  intermontane  plains. 

The  principal  occurrences,  as  described  by  Brackebusch,66 
Stappenbeck,67  and  particularly  by  Bodenbender,68  are  to  be  found 
between  the  extremity  of  the  Gerro  Villa  Union  and  the  Sierra  del 
Valle  Fertil,  on  the  western  and  southern  sides  of  the  Sierra  de  Vilgo 
and  Sierra  de  Sanogasta,  at  the  southern  end  of  the  Sierra  de  la 
Huerta,  around  the  greater  part  of  the  edge  of  the  Sierra  de  Chepes  and 
Sierra  de  los  Llanos  and  in  small  areas  in  the  Sierra  Brava,  Sierra  de 
Cordoba,  and  at  Bajo  de  Velis  in  the  Sierra  de  San  Luis.  To  the  north¬ 
west  they  are  represented  in  the  Sierra  de  Umango  and  beyond  in 
the  Puna  de  Atacama  up  to  the  border  of  Bolivia,  while  to  the  north¬ 
east  they  reappear  in  Tucuman,  Jujuy,  and  Oran,  and  thence  have  a 
lengthy  distribution  far  to  the  north,  as  will  be  set  forth  in  section  G. 
Bore-holes  in  the  northern  and  northeastern  parts  of  Argentina  sug¬ 
gest  that  they  may  occupy  a  considerable  tract  beneath  the  thick 
covering  of  Neogene,  possibly  even  joining  up  underground  with  the 
known  extension  of  the  Santa  Catherina  system  into  the  territory 
west  of  the  lower  Parana  River. 

(5)  The  Stratigraphy  of  the  Paganzo 

The  system  can  be  divided  into  four  “ pisos  ”  or  stages ,  the  first  of 
upper  Carboniferous,  the  second  and  third  of  Permian,  and  the 
fourth  of  Trias-Rhsetic  age,  though  extending  probably  into  the 
Liassic,  with  the  very  uppermost  portion  thereof  regarded  tentatively 
as  constituting  stage  V. 

Stage  I — This  generally  ranges  between  150  and  300  meters  in 
thickness,  though  probably  well  exceeding  that  value  in  San  Juan, 
where,  as  remarked  above,  lower  horizons  would  seem  to  be  present. 
On  the  other  hand,  in  certain  places  it  is  thin  or  even  absent,  owing 
to  the  transgression  of  higher  beds,  occasionally  even  those  of  stage 
II.  Thus  in  the  valley  of  the  Rio  Nogues  to  the  east  of  Cerro  Villa 

66  Brackebusch  (1891)  and  geological  map  (1892). 

67  Stappenbeck  (1913,  I91?,  1920)- 

68  Bodenbender  (1897,  1902,  1911,  1912,  1916). 


44  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

Union  the  upper  conglomerate,  lying  just  below  Stage  II,  rests  on  the 
crystalline  schists,  while  farther  to  the  east,  in  the  neighborhood  of 
Sanogasta  (Nevado  de  Famatina),  Stage  II  rests  on  granite  or 
quartz-porphyry.  Furthermore,  in  the  Puna  de  Atacama,  Penck  69 
has  observed  the  red  sandstone  of  Stage  III  reposing  directly  upon 
granite  in  the  Cerro  Negro  de  los  Andes  (west  of  Tinogasta)  and 
Cerro  Palca,  more  to  the  north. 

In  the  extreme  west  there  are  developed  at  the  base  of  the  system 
the  glacials  detailed  earlier,  having  an  intercalated  zone  with  plants 
of  middle  and  upper  Carboniferous  genera  and  species,  but,  while 
stratified  conglomerates  (particularly  well  developed  in  the  Sierra 
de  los  Llanos  for  example) ,  arkoses,  and  gray,  yellowish,  and  greenish 
sandstones  occur  in  this  inferior  position  toward  the  east,  Boden- 
bender  has  stated  that  he  had  observed  no  evidences  of  glaciation  in 
them.  Penck’s  note  of  an  unstratified  boulder  deposit,  like  a  tillite, 
close  to  Angulos,  a  little  north  of  Famatina,  indicates  the  possible 
existence  of  glacial  material  in  that  quarter.  At  Bajo  de  Velis 
glacials  are  absent  at  the  bottom  of  the  system. 

Not  improbably  the  prevailing  conditions  are  rather  like  those 
that  have  been  made  out  in  South  Africa  in  passing  from  Natal  to 
the  Transvaal,  where,  owing  to  the  uneven  nature  of  the  (glaciated) 
floor  and  to  a  temporary  “post-glacial”  exposure  of  the  latter,  coarse 
fluviatile  sediments  have  come  to  overlap  on  to,  and  rest  upon,  the 
glaciated  land  surface,  and  the  morainic  deposit  is  only  to  be  found 
preserved  in  the  deeper  hollows  in  the  latter. 

Above  this  coarse  basal  phase  in  Argentina  is  a  conspicuous  zone 
of  carbonaceous  shales  with  thin  coaly  streaks  and  layers,  sometimes 
pyritic  in  its  nature.  It  is  followed  by  sandstones  (as  in  the  Cerro 
Villa  Union),  by  conglomerates  with  porphyry  pebbles,  and  by  means 
of  a  hard  white  sandstone  passes  up  by  degrees  and  quite  conformably 
into  Stage  II.  Some  calcareous  and  siliceous  concretions  are  to  be 
found  and  also  thin  beds  of  limestone  in  the  Sierra  de  los  Llanos. 
The  carbonaceous  zone  alluded  to  is,  as  Bodenbender 70  has  remarked, 
a  constant  feature,  and  has  yielded,  as  already  stated, the  Glossopteris 
flora  at  a  number  of  points,  e.g.,  Sierra  de  los  Llanos  and  Bajo  de 
Velis  (Plate  VIII,  B),  an  association  strikingly  like  that  of  the  Bonito 
series  of  Brazil  succeeding  the  Itarare  glacial  series  of  that  country, 
and  which,  from  external  evidence  very  largely,  we  have  to  place  at 
the  top  of  the  Carboniferous. 

Stage  II — Not  less  than  300  and  probably  up  to  500  meters  in 
thickness,  it  is  distinguished  from  the  older  group  by  the  brilliant 
coloring  of  the  beds — rose,  red,  gray,  white,  etc. — by  clayey,  cal¬ 
careous,  and  siliceous  strata,  fine-grained  red  and  partly  white  sand¬ 
stones,  thin  quartzites,  and  bands  of  limestone  up  to  some  meters 

69  Penck  (1920),  p.  134.  70  Bodenbender  (1911),  p.  64. 


ARGENTINA  AND  BOLIVIA 


45 


thick,  and  silicified  marls.  The  calcareous  matter  may  occur  in  the 
form  of  concretions  and  lenses  and  is  often  dolomitic ;  partial  silicifi- 
cation  has  caused  the  strata  (particularly  in  the  middle  of  the  group) 
to  resemble  on  weathering  mottled  felsites,  while  oolitic  structure  is 
common;  especially  is  this  the  case  in  La  Rioja,  though  this  phase  is 
not  known  in  Catamarca. 

This  group  is  not  fossiliferous,  but  in  its  lithological  characters 
recalls  the  divisions  of  the  Iraty  and  Estrada  Nova  (Passa  Dois) 
series  of  Brazil  and  Uruguay,  more  particularly  as  developed  in  the 
latter  country.  Its  age  is  probably  lower  Permian. 

Stage  III — Transitional  from  the  foregoing  and  from  300  to  500 
meters  in  thickness,  come  quartzitic  sandstones,  dark  arkoses,  and 
conglomerates  (particularly  towards  the  top),  while  the  softer  beds 
are  darker  and  there  is  less  calcareous  matter  present,  but  lime¬ 
stone — occasionally  silicified — still  occurs  and  gypsum  is  sometimes 
found,  as  in  the  Puna  de  Atacama.  On  several  horizons,  both  in  this 
and  in  Stage  II,  have  been  recorded  contemporaneous  basaltic  flows, 
also  augite-porphyrite  and  occasionally  tuff,  for  example,  in  the 
Troya  Valley  (Puna  de  Atacama),  Cerro  Villa  Union,  Cerro  Bola, 
and  at  and  to  the  north  of  Paganzo— forerunners  obviously  of  the 
marked  volcanicity  of  the  late  Triassic. 

Unusual  interest  attaches  to  its  development  in  the  Puna  de 
Atacama,  where,  according  to  Penck,71  a  thickness  of  over  900  meters 
is  represented  with  some  melaphyres  at  the  top,  the  red-brown  sand¬ 
stones  being  fine-grained  and  diagonally-bedded  to  platy,  while  the 
calcareous  thin-bedded,  fine-grained  beds  carry  siliceous  layers  and 
concretions  and  gray,  red,  and  violet  “marls,”  observations  which 
suggest  that  this  succession  actually  includes  part  of  the  Trias- 
Rhaetic  Stage  IV,  and  may  even  be  in  part  equivalent  to  the  Estrada 
Nova  and  Rio  do  Rasto  of  Brazil.  In  a  remarkable  facies  arising 
through  alteration  by  granite,  these  reddish  beds  have  been  con¬ 
verted  into  gray,  yellow,  red,  and  violet  quartzites  containing  a  fos¬ 
siliferous  zone  of  white  porcellanous  shales  in  the  lofty  Tolarcito 
Pass  (lat.  2 70  15'),  which  has  yielded  a  scanty  marine  fauna  (Ana- 
plophora ,  Avicula,  etc.),  indicating  a  Triassic  age.72  These  are  the 
only  fossils  known  from  this  stage,  and  should  be  compared  with 
those  from  the  Estrada  Nova  (see  page  150). 

Stage  IV,  the  Trias-Rhxtic — The  so-called  “Rhaetic  beds” — as 
usually  indicated  by  the  presence  of  the  ‘  ‘  Thinnfeldia  flora  ’  ’ — out¬ 
crop  in  quite  a  number  of  places  between  Mendoza  in  the  south  and 
Famatina  in  the  north  and  between  the  Andes  in  the  west  and  perhaps 
Cordoba  in  the  east,  though  occupying  a  more  restricted  area  than 
the  older  stages.  In  the  northern  half  of  Patagonia,  however,  their 
equivalents  have  been  found  to  make  a  wide  distribution. 

71  Penck  (1920),  pp.  132-133.  72  Penck  (1920),  p.  151. 


46  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

As  mentioned  already,  the  late  Permian  or  early  Triassic  earth 
movements  (Gondwanides)  led  to  the  folding  and  to  the  subsequent 
erosion  of  the  lower  stages  of  the  Paganzo,  and  so  enabled  the  suc¬ 
ceeding  Mesozoic  formations  to  transgress  across  the  edges  of  the 
latter.  At  quite  a  number  of  places  the  unconformable  relationship  of 
the  younger  beds  can  be  studied,  but  in  the  northwest,  in  the  but 
little  disturbed  tract  between  the  Sierra  de  Paganzo  and  the  Cerro 
Villa  Union,  there  is  reported  to  be  an  apparently  unbroken  succes¬ 
sion  from  Stage  III  into  Stage  IV,  and  from  the  latter  in  turn  into 
beds  that  may  just  possibly  be  Jurassic,73  tentatively  referred  to  as 
Stage  V. 

This  region  embraces  by  far  the  largest  continuous  area  in  the 
pre-Cordillera,  the  other  widely  scattered  localities  being  those  at 
Barreal  and  Jarillal  in  the  valley  of  the  Rio  de  los  Patos  west  of  San 
Juan;  the  important  elevated  mass  of  the  Paramillo  overlooking  the 
Uspallata  Valley;  Salagasta,  San  Isidro,  Challao,  Potrerillos,  and 
Cacheuta  among  the  foot-hills  of  the  Mendoza  district ;  and  Marayes 
on  the  southwest  side  of  the  Sierra  de  la  Huerta ;  but  not  in  the  Sierra 
de  los  Llanos  or  Sierra  de  San  Luis.  This  stage  is  only  doubtfully 
present  in  the  Sierra  de  Umango  and  is  not  known  in  the  Nevado  de 
Famatina,  though  it  has  its  equivalent  farther  to  the  northeast  and 
north  in  the  districts  of  Tucuman,  Jujuy,  and  onward  into  Bolivia, 
to  which  reference  will  be  made  below.  In  the  east,  beds  regarded  as 
Triassic  are  known  in  various  parts  of  the  Sierra  de  Cordoba,  while 
the  deep  bore-hole  at  Alhuampa  on  the  Central  Norte  Railway  in 
Santiago  del  Estero  proved  nearly  flat-lying  Trias-Rhaetic  ( ?)  beds 
from  the  depth  of  about  1,340  meters  downward,  having  Permian 
most  probably  (with  Schizoneura  and  Phyllotheca )  below  1,700  meters 
down  to  2,111  meters — a  link  with  the  strata  forming  the  vast 
Triassic  plateau  of  Uruguay  and  Paraguay. 

In  the  main  region  between  Cerro  Villa  Union  and  the  Sierra  de 
Paganzo,  Bodenbender  has  recorded  this  stage  as  extending  along 
the  eastern  side  of  the  Cerro  Bola,  dipping  eastward  and  covering 
the  wide  stretch  made  by  the  Cerro  Totorilillo,  wrapping  around 
the  northern  end  of  Sierra  del  Valle  Fertil,  reaching  almost  to  the 
Sierra  del  Cerro  Blanco,  and  occurring  again  on  the  eastern  side  of  that 
range  of  crystallines,  where,  at  El  Molle,  it  reposes  upon  conglomer¬ 
ates  taken,  though  not  without  some  doubt,  as  the  top  of  Stage  III ; 
the  same  relationship  is  seen  in  the  Cerro  Morado  a  little  to  the  west 
and  again  on  the  eastern  side  of  the  Cerro  Bola.  A  thickness  of 
between  400  and  500  meters  is  represented,  consisting  of  gray  arkoses 
and  yellow  sandstones,  from  coarse  to  fine,  with  intercalations  of 
carbonaceous  shales,  carrying  plant  remains,  chiefly  Thinnfeldia, 
and  a  seam  of  coal  about  1  meter  thick  on  the  western  side  of  the 

73 Bodenbender  (1911),  p.  124. 


ARGENTINA  AND  BOLIVIA 


47 


Cerro  Morado  and  impure  seams  at  Marayes  farther  to  the  south. 
In  addition,  intercalated  flows  of  olivine-basalt  are  known  on  at 
least  two  horizons,  such  volcanic  rocks  crowning  some  of  the  ridges, 
such  as  the  Cerro  Morado.  These  beds  are  most  probably  of  Upper 
Triassic  age. 

The  group  is  followed  with  complete  conformity  by  Stage  V,  some 
400  to  500  meters  of  strata,  including  marls  with  many  calcareous 
nodules  and  sometimes  of  concretions  of  barite,  by  sandstones,  and 
by  whitish-yellow  or  grayish,  white,  red,  and  green  clays,  passing  up 
into  light  sandstone,  and  by  brilliant  red  sandstones  and  clays  with 
gypsum.  Trunks  of  Araucarian  type  have  been  recorded  from  a 
point  east  of  the  Sierra  de  Cerro  Blanco.  Bodenbender  has  proposed  a 
Jurassic  age  for  the  lower  part  of  this  division  and  a  Cretaceous  one 
for  the  upper  part,  but  there  seem  to  be  no  valid  reasons  why  these 
strata  should  not  be  Rhaeto-Lias,  as  is  suggested  by  the  sections 
near  Barreal. 

At  Hilario,  a  little  to  the  north  of  that  village,  I  found  Stage  IV 
resting  unconformably  on  tilted  lower  Palaeozoics,  its  base  being 
crowded  with  chips  of  green  slates  and  greywackes  derived  there¬ 
from,  followed  by  sandstones  with  cherty  layers  and  dark  fissile 
cherts,  white  shales,  thin  layers  of  volcanic  ash,  grits,  and  some  con¬ 
glomerates.  In  the  Quebrada  del  Jarillal,  a  few  kilometers  to  the 
south,  higher  beds  are  finely  exposed  (Plate  IX,  A),  with  soft  vari¬ 
egated  shales  and  dark  shales  carrying  numerous  well-preserved 
plants  ( Thinnfeldia ,  Txniopteris,  Baiera ,  Cladophlebis,  Phcenicopsis , 
etc.,  and  silicified  wood,  probably  Dadoxylon )  and  some  torbanite- 
like  bands.  Similar  soft  gray  beds  appear  in  the  Quebrada  del  Salto 
due  east  of  Barreal,  wherein,  below  a  band  of  gray  clays  with  Thinn¬ 
feldia ,  were  found  some  lenses  of  a  green  rock  with  what  seemed  to  be 
traces  of  marine  fossils,  though  not  identifiable.  Both  here  and  at  the 
Quebrada  del  Jarillal  these  plant-bearing  beds  are  followed  by  vivid 
red  conglomerates  and  sandstones  (Stage  V,  Plate  IX,  B),  which, 
though  regarded  by  Stappenbeck 74  as  Cretaceous,  appear  to  be  quite 
conformable,  there  being  an  actual  interlamination  of  pink  and  gray 
clays  with  small-pebble  conglomerate  about  the  junction,  a  character 
to  be  found  duplicated  in  the  Mendoza  district. 

Time  only  permitted  of  a  single  rapid  traverse  across  the  high- 
lying  Paramillo  region,  described  originally  by  Stelzner 75  and  Ave- 
Lallemant 76  and  briefly  by  Stappenbeck.77  On  the  east,  resting  upon 
tilted  Devonian  (?)  slates,  one  finds  gently  inclined  hard  sandstones, 
arkoses,  and  greenish  shales  in  which  Keidel 78  has  discovered  Cyzicus 
(. Estheria ),  like  the  beds  characterizing  the  middle  of  the  group  at 

74  Stappenbeck  (1910),  pp.  56,  66.  77 Stappenbeck  (1910),  pp.  60-61. 

75  Stelzner  (1878).  78  Verbal  communication. 

76  Av6-Lallemant  (1890). 


48  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

Challao,  overlain  by  andesitic  lavas,  and  followed  by  similar  sedi¬ 
ments  to  a  total  thickness  of  several  hundred  meters.  Conspicuous 
is  a  splendid  section  along  the  main  road,  displaying  a  large  number 
of  coniferous  tree-trunks  (probably  Dadoxylon) ,  standing  upright 
(Plate  X,  A),  rooted  in  a  sandstone  bed  and  surrounded  by  drab- 
colored  tuff,  above  which  comes  a  sandstone  which  the  stems  do  not 
penetrate.  This  horizon  was  noticed  by  Ave-Lallamant  and  termed 
by  him  “the  sandstone  with  Araucarias.  ”  On  the  water-shed  these 
beds  give  place  to  a  group  of  thin  sandstones,  dark  shales,  and 
bituminous  shales  with  tuffs  and  basaltic  intercalations  to  a  thickness 
of  perhaps  120  or  150  meters.  The  bituminous  shales  occur  as  thin 
bands,  weathering  with  a  bluish-gray  or  white  exterior  and  brownish 
to  blackish  interior,  giving  out  a  wooden  sound  when  struck  with  the 
hammer;  they  are  clearly  allied  to  the  torbanites,  and  are  crowded 
with  the  carapaces  of  Estheria  and  contain  occasional  scales  of 
Semionotus.  Some  thin  limestones  and  cherts  have  been  recorded 
from  these  beds  by  Stappenbeck,  while  plants  have  been  obtained  at 
a  number  of  points,  including  Thinnfeldia,  Tasniopteris,  Baiera ,  etc. 

That  the  basaltic  layers  are  extrusive,  though  generally  quite 
compact,  is  shown  by  the  presence  of  small  vesicles  either  at  top  or 
base,  or  in  some  instances  by  a  zone  of  “pipe-amygdaloid”  at  the 
bottom,  and  by  the  fact  that  the  shales  may  rest  in  the  unaltered 
state  on  a  slightly  uneven  surface  of  the  igneous  rock.  In  addition 
to  these  lavas,  intrusive  sills  of  andesite  cut  these  beds. 

In  the  Cerro  Colorado,  lying  to  the  west,  the  plant-bearing  shales 
and  white  and  gray  tufaceous  sandstones  pass  up  into  red  and  green 
clays  and  false-bedded  red  sandstones  with  clays,  pierced  and  over- 
lain  by  intrusive  andesite,  these  strata  being  viewed  by  Stappen¬ 
beck  as  Cretaceous,  but  being  more  probably  of  Rhsetic  or  Liassic 
age.  The  total  thickness  of  the  sediments  involved  in  the  Para- 
millo  ascribable  to  Stages  IV  and  V  may  perhaps  possess  a  value  of 
1,000  meters. 

At  Challao,  7  km.  to  the  northwest  of  Mendoza,  the  succession, 
which  I  estimate  to  be  not  less  than  450  meters  in  thickness,  begins 
with  a  massive  basal  conglomerate,  deep  red  in  color,  resting  on 
tilted  Palaeozoics,  passing  up  through  red  sandstone  and  pale  sand¬ 
stone  and  greenish  shales,  arkoses,  etc.,  into  a  group  of  well  laminated 
shales,  banded  cherty  shales,  dark  “papery  shales,”  and  torbanite- 
like  layers  standing  almost  vertically,  of  which  latter  thin-bedded 
strata  some  details  are  given  by  Stappenbeck,  and  ending  in  a  thick 
mass  of  sandstones  of  red  or  gray- violet  tint,  so-called  “Cretaceous.  ” 
Noteworthy  is  the  abundance  of  Estheria  ( E .  draperi  and  not  E. 
mangliensis) ,  not  only  in  the  shales  and  gray  cherty  layers,  but  in 
the  associated  sandstone  beds  and  carbonaceous  bands.  The  latter 
are  much  weathered  and  plant  remains  are  hence  difficult  to  obtain 


ARGENTINA  AND  BOLIVIA 


49 


03 


>  * 

k 


\ 


V 

x 


vsv:-; 


now;  Cladophlebis  mesozoica  Kurtz  has  been  recorded  here,  while 
Keidel  has  discovered  remains  of  Gyporella  in  a  gray  dolomite.79  In 

a  block  of  yellowish  sandstone  from  a  horizon 
about  midway  in  the  group  and  at  least  200 
meters  below  the  Estheria  beds — unfortunately 
too  large  to  be  removed — I  obtained  on  develop¬ 
ment  an  impression  of  Glossopteris,  probably  G. 
angustifolia,  a  long  pinna  of  Marattiopsis ,  prob¬ 
ably  allied  to  M.  muensteri,  and  a  large  equiseta- 
ceous  stem,  which  would  indicate  a  Triassic  age 
for  this  part  of  the  formation. 

At  Potrerillos,  on  the  Transandine  Railway 
o  kv  "K  *  •  between  Mendoza  and  Uspallata,  is  to  be  found 

a  very  similar  and  complete  section  in  the  Cerro 
de  las  Cabras  displaying  fully  700  meters  of  beds 
dipping  southward  at  moderately  high  angles 
(Fig.  5),  wdiich,  in  the  light  of  the  foregoing  de¬ 
scriptions,  I  am  inclined  to  interpret  differently 
to  Stappenbeck.80  The  formation  is  underlain  by 
porphyritic  and  other  volcanics  (a)  and  com¬ 
mences  with  deep-red  conglomerates  and  small 
pebble  breccias  some  150  meters  thick  ( b ),  fol¬ 
lowed  by  transitional  beds  of  pink  clays  and 
grits  (c)  into  yellow  sandstones,  grits,  gray  shales 
and  mudstones  (d),  from  the  midst  of  which 
Estheria  and  Thinnfeldia  were  collected  at  (e). 
Conspicuous  is  next  a  red  small-pebble  conglom¬ 
erate  (/)  and  some  distance  above  that  a  body 
of  15  meters  of  black  and  gray  shales  with  car¬ 
bonaceous  mudstones  (g)  yielding  scales  of 
Semionotus ,  passing  up  without  a  break  into 
dark-maroon  shales  (h)  with  yellow  sandstones 
*'oo  ^  (i),  after  which  appear  vermilion  grits  and  small- 

pebble  conglomerates  (j),  seemingly  the  beds 
regarded  by  Stappenbeck  as  Cretaceous. 

There  is,  however,  no  break  discernible  in 
the  entire  succession  and  the  alternation  of  deep 
red  with  the  normal  and  often  black  strata,  ex¬ 
ceptionally  well  seen  in  the  Cerro  Bayo,  would 
show  that  this  upper  and  predominantly  red  for¬ 
mation  must  be  perfectly  conformable  with  the 
beds  below  and  consequently  ought  to  be  grouped 
with  the  Paganzo,  though  it  could  very  con- 

79  Stappenbeck  (1910),  p.  62. 

80 Stappenbeck  (1917),  p.  21. 


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50  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

veniently  be  considered  as  forming  *  ‘  Stage  V.  ”  At  Potrerillos  it  is 
overlain  with  a  break  by  the  tilted  Pliocene  “  Calchaquenos.  ” 

At  the  southern  end  of  the  Cerro  de  Cacheuta,  20  km.  to  the 
southeast,  is  the  classic  section  at  the  back  of  the  Mina  de  Petroleo.81 
Here  the  beds  dip  at  20°  to  the  south,  displaying  at  their  base 
porphyritic  lavas  and  keratophyres,  then  35  meters  of  tufaceous 
sandstones,  15  meters  of  bituminous  shales  (lower),  20  meters  of 
sandstones,  and  8  meters  of  thin-bedded  gray  shales  with  plants,  73 
meters  of  coarse  sandstones,  gray  conglomeratic  sandstones,  etc., 
70  meters  of  bituminous  shales  (upper),  while  quite  conformably 
above  come  130  meters  of  red,  gray,  and  violet  and  gray  sandstones 
and  shales  with  some  gypsiferous  bands  (Stage  V),  overlain  by  a  great 
mass  of  Tertiaries.82  Plants  are  best  preserved  in  the  gray  shales  and 
scarcely  in  the  highly  carbonaceous  bands — most  abundantly 
Thinnfeldia ,  Baiera ,  Cladophlebis,  Stenopteris,  etc.83  Striking  is  the 
abundance  of  Cyzicus  (. Estheria )  draperi  Jones,  with  which  the  bitum¬ 
inous  shales  are  crowded,  and  which  organism  has  not  improbably 
been  responsible  for  the  petroleum  seeping  out  from  the  outcrop  of 
the  lower  shales,  also  struck  in  bore-holes  to  the  south  beneath  the 
Tertiary  covering,  in  the  sandstones  overlying  those  shales,  where 
the  formation  has  been  bent  into  a  dome.  The  petroleum  is  un¬ 
usually  high  in  its  content  of  paraffin  wax. 

Occurrences  Outside  the  Pre-Cordillera — Most  illuminating  are 
certain  localities  where  the  Trias-Rhaetic  is  present  in  the  Cordillera 
of  Chile  and  Argentina  and  also  in  Patagonia. 

Of  particular  interest  is  the  isolated  patch  at  La  Ternera,84 
northeast  of  Copiapo  (lat.  270  12',  long.  69°  50'),  where,  in  perfect 
conformity  beneath  nearly  vertical  tuffs  including  a  limestone  bed 
carrying  a  decidedly  lower  Liassic  marine  fauna,  comes  a  50-meter- 
thick  group  containing  conglomerates  with  porphyry  pebbles,  sand¬ 
stones,  shales  with  cherty  bands,  clay  ironstone,  and  impure  coals 
in  layers  and  streaks,  the  bottom  in  contact  with  a  mass  of  porphy- 
rite,  apparently  intrusive.  From  this  group,  which  lithologically 
shows  close  resemblances  with  the  occurrences  in  the  San  Juan  and 
Mendoza  districts,  Solms-Laubach  has  described  a  flora  with 
Thinnfeldia ,  Txniopteris,  etc.,  while  Estheria  also  occurs,  and  fossil 
wood.  The  horizon  represented  here  must  undoubtedly  be  the 
Rhaetic,  and,  significantly,  includes  certain  genera  not  known  in 
Argentina,  such  as  Dictyophyllum,  Lesley  a }  Clathropteris,  Copiapxa ,  etc. 

The  presence  of  the  upper  Triassic  ocean  is  proved  to  the  south¬ 
west  by  the  finding  on  the  Rio  de  Huasco  of  beds  resting  directly  on 
granite  and  crystalline  schists  (of  which  they  carry  pebbles)  con- 

81  Stappenbeck  (1910),  p.  65;  (1917),  pp.  22,  45. 

82  From  a  measured  section  furnished  me  by  Mr.  H.  J.  Hawley. 

83  Szajnocha  (1888). 

84Steinmann  and  Solms-Laubach  (1899). 


ARGENTINA  AND  BOLIVIA 


51 


taining  Halobia ,  while  farther  down  the  coast,  near  the  Rio  Choapa, 
Groeber 85  has  discovered  strata  containing  that  genus  and  also  Pseu- 
domonotis ,  as  well  as  older  beds  of  Permian  or  more  probably  Car¬ 
boniferous  age  carrying  Productus. 

Groeber 86  has  summarized  information  on  the  supra-Triassic  and 
pointed  out  that  at  Puente  del  Inca,  Rio  de  las  Vacas,  and  the  region 
of  Espinacito  to  the  west  of  Uspallata  the  Callovian,  Dogger,  or  Lias 
overlap  quartz-porphyries,  porphyrites,  and  melaphyres  belonging  to 
Stage  IV  (or  V)  which  rest  discordantly  on  possibly  Devonian  rocks, 
while,  as  remarked  earlier,  they  appear  again  in  the  Sierra  Pintada 
to  the  south  and  are  of  importance  in  the  area  between  the  Rio  Atuel 
and  the  Rio  Neuquen,  where  they  are  covered  by  Liassic  or  Jurassic 
marine  beds,  the  “Paganzo”  (with  its  original  significance)  being 
absent ;  quartz-porphyries  and  tuffs  here  play  a  very  important  role. 
Groeber  regards  this  mainly  volcanic  assemblage  of  the  Cordillera, 
extending  roughly  north  and  south  and  having  a  thickness  of  up  to 
i,ooo  meters,  as  wholly  of  upper  Triassic  age,  but  points  out  that 
there  are  actually  similar  volcanics  in  the  overlying  Liassic  as  well. 
Of  immense  importance  is  his  discovery  that  near  Las  Lajas  (lat. 
39°,  long.  710)  on  the  Chilean  border  the  first-mentioned  group  of 
volcanics  succeed  marine  middle  or  upper  Triassic  beds,  which  are 
resting  unconformably  on  the  ancient  platform,  and  that  the  Dogger 
overlies  these  volcanics  and  has  a  basal  conglomerate  with  pebbles 
derived  from  the  latter.87 

From  the  sub-Andine  zone  in  Chubut  (Patagonia)  to  the  south¬ 
east,  Keidel 88  has  described  crystal  tuffs,  brilliantly  colored  tuffs, 
calcareous  shales,  etc.,  crowded  with  Estheria  draperi.  Porphyrites, 
agglomerates,  and  tuffs  are  mentioned  by  Rassmuss 89  at  the  head  of 
the  Rfo  Chubut,  while  similar  beds  are  recorded  by  Windhausen 90 
from  the  Rfo  Chubut,  the  neighborhood  of  Sarmiento,  and  from  the 
Rfo  Deseado,  San  Julian,  and  other  places  farther  south  in  Santa 
Cruz.  Quartz-porphyries,  rhyolitic  rocks,  and  keratophyres  are 
known  in  various  places,  but  it  is  somewhat  difficult  from  a  study  of 
the  literature  alone  to  obtain  a  clear  idea  as  to  the  precise  relation  of 
these  effusions  to  the  pyroclastic  rocks,  more  especially  as  Rassmuss 
remarks  that  bodies  of  intrusive  granite  and  grano-diorite,  probably 
of  Jurassic  age,  occur  in  the  upper  part  of  the  Rfo  Chubut.  It  is 
certain,  however,  that  this  assemblage,  with  a  maximum  recorded 
thickness  on  the  coast  of  over  900  meters,  rests  upon  the  crystalline 
basement  and  has  been  bent  into  moderate  folds  along  arcs  trending 
roughly  south-southeast  to  southeast  as  the  result  of  movements 
during  the  mid-Cretaceous,  and  are  overlain  unconformably  by 

“Groeber  (1922).  “Keidel  (1917-18). 

“Groeber  (1918),  pp.  49-59.  89 Rassmuss  (1922). 

87  Verbal  communication.  90  Windhausen  (1921,  1924). 


52  GEOLOGICAL  COMPARISON  OP  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

almost  undisturbed  upper  Cretaceous,  Tertiary,  or  Quaternary; 
they  moreover  show  out  at  intervals  over  a  great  area  stretching 
southward  into  Terra  del  Fuego. 

The  presence  of  Cyzicus  (. Estheria )  draperi  and  of  silicified  wrood 
enables  comparison  to  be  made  with  the  so-called  “Rhaetic”  of  the 
Mendoza  district.  In  the  latter  are  to  be  found  the  beginnings  of  the 
acid  effusions  and  fragmental  rocks  that  have  such  a  development  to 
the  south  and  southeast,  though  not  represented  in  other  parts  of 
South  America.  In  South  Africa,  however,  are  the  comparable  and 
immense  acid  outpourings  of  the  Lebombo  on  the  southeastern  side 
of  that  continent,  with  certain  intrusive  granophyric,  felsitic,  and 
dioritic  masses,  all  of  Stormberg  age  (Rhaeto-Lias) ,  while  at  Brisbane 
in  Queensland  the  base  of  the  Triassic  Ipswich  series  is  made  by  a 
bed  of  quartz-porphyry  tuff  resting  on  the  vertical  edges  of  schists, 
while  rhyolites,  dacites  and  andesites  are  also  known  from  this 
neighborhood. 

A  matter  to  which  attention  should  be  drawn  is  the  presence  in 
the  southwestern  corner  of  the  Neuquen  district  of  Neocomian  beds 
carrying  molluscan  fossils  typical  of  the  Uitenhage  series  of  the 
Cape,  such  as  Holcostephanus  atherstonei,  H.  rogersi,  H.  uitenhagensis , 
Trigonia  ventricosa,  T.  aff.  rogersi ,  T.  transitoria  allied  to  T.  hertzogi , 
T.  eximia  allied  to  T.  conocar diiformis,  T.  pusilla  and  other  forms 
related  to  T.  van,  Grammatodon  jonesi,  Exogyra  imbricata ,  etc.91 

This  locality,  situated  to  the  southwest  of  the  arc  of  the 
“  Gondwanides,  ”  shows  therefore  a  very  close  analogy  with  the  geol¬ 
ogy  of  the  Uitenhage  district  of  the  Cape,  as  will  be  discussed  at 
a  later  place. 

The  Occurrences  in  the  Pampean  Ranges — Constituting  a  link 
between  the  west  and  the  center  are  the  exposures  at  Marayes  along 
the  southern  base  of  the  Sierra  de  la  Huerta,  where,  sandwiched 
between  two  groups  of  chocolate-  and  maroon-colored  conglomeratic 
strata,  come  some  150  meters  of  greenish  and  buff  sandstones  with 
thin  shales  and  coals  (the  so-called  “Rhaetic,”  Plate  X,  B)\  the 
basal  group  rests  upon  an  uneven  surface  of  the  crystallines.  In  the 
sections  exposed  at  the  Rickard  Mine  and  at  Carrizal  there  seemed 
to  me  to  be  a  conformable  succession,  but  according  to  Rassmuss 
what  would  appear  to  be  an  intraformational  unconformity  is  present, 
the  ‘  ‘  Rhaetic  ’  ’  transgressing  across  the  lower  group  of  the  ‘  ‘  Paganzo  ’ ’ 
and  coming  to  rest  directly  upon  the  crystallines  when  followed 
toward  the  north.92  The  upper  group  of  deeply  colored  rocks,  fully 
400  meters  thick,  is  referred  to  by  him  as  of  Cretaceous  age,  but  since 
it  recalls  the  succession  already  described  in  the  region  to  the  west, 
and  appears  to  follow  conformably  upon  the  Rhaetic  within  this 

9X  Letter  written  me  by  Dr.  Pablo  Groeber  dated  June  7,  1926. 

92  Rassmuss  (1922a). 


ARGENTINA  AND  BOLIVIA 


53 


trough,  it  can  provisionally  be  considered  as  forming  the  uppermost 
portion  of  the  Paganzo  system,  Stage  V.  The  assemblages  can  hence 
be  placed  in  the  Trias-Lias  succession.  The  coals  at  the  Rickard 
Mine  and  at  Carrizal  are  very  thin,  high  in  ash,  and  extremely  pyritic. 
In  addition  to  calcified  coniferous  stems,  the  middle  group  has 
yielded  the  Thinnfeldia  flora,  this  being  the  most  southeasterly  point 
where  such  has  been  recorded  in  Argentina,93  with  the  probable 
exception  of  the  strata  with  Cladophlebis  mesozoica  resting  on  the 
granite  in  the  Sierra  de  los  Llanos.94 

Turning  attention  to  the  Central  Pampean  ranges,  the  eastern¬ 
most  outcrop  of  beds,  that  on  lithological  grounds  have  been  ascribed 
to  the  Triassic,  are  to  be  found  in  the  Sierra  de  Cordoba,95  forming 
a  series  of  patches  resting  upon  an  uneven  surface  of  gneiss,  Palaeo¬ 
zoic  (?)  limestones,  etc.,  in  some  places  horizontally,  in  others  tilted 
and  faulted.  At  Saldan,  just  north  of  Cordoba,  the  series  consists  of 
ioo  meters  of  red  conglomerates,  passing  up  into  deep-red  sandstones 
with  some  red  shaly  layers  (Plate  XI,  A).  Ripple-marked  and  sun- 
cracked  surfaces  are  present  and  the  sandstones  are  markedly  cross- 
bedded,  recalling  the  upper  Triassic  seen  elsewhere.  In  Los  Terrones, 
northeast  of  Capilla  del  Monte,  are  splendid  sections  through  at  least 
200  meters  of  red  conglomeratic  beds,  weathered  out  into  striking 
erosional  forms  (Plate  XI,  B).  The  gneiss  surface  beneath  is  highly 
uneven  and  the  junction  here  is  not  a  faulted  one,  as  maintained  by 
Rimann.96  Some  volcanic  rocks  overlie  the  strata  at  La  Cumbre,  but 
the  circumstances  rather  suggest  an  unconformable  relationship  and 
a  much  younger  age. 

Provisionally  these  sediments  can  be  allotted  to  the  top  of  the 
Paganzo,  but,  inasmuch  as  coals  are  reported  to  occur  to  the  south 
of  Cordoba  along  the  line  of  strike  of  the  Saldan  conglomerates, 
plants  should  shortly  be  forthcoming  to  decide  this  question,  which 
is  an  important  one,  since  these  are  the  easternmost  outcrops  of 
such  beds  in  the  republic. 

The  Thinnfeldia  Flora — Some  remarks  might  be  made  on  the 
composition  of  this  flora  and  its  bearing  on  the  age  of  the  inclosing 
strata. 

The  several  florules  in  western  Argentina,  occurring  as  they  do 
each  in  a  group  of  gray  or  carbonaceous  shales,  sometimes  accom¬ 
panied  by  impure  coals,  sandwiched  between  groups  of  coarser  vari¬ 
egated  sediments,  represent  with  but  little  doubt  practically  one  and 
the  same  horizon  situated  not  very  far  from  the  middle  of  Stage  IV, 
being  followed  by  the  red  strata  placed  by  me  in  Stage  V,  correlated 
provisionally  with  the  Botucatu  of  Brazil. 

From  those  sections  of  Gondwanaland,  that  possess  beds  carry- 


93Geinitz  (1876);  Gothan  (1925). 

84  Vide  Keidel  (1922),  pp.  288-290. 


95  Bodenbender  (1905). 

96  Rimann  (1918). 


54  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

ing  the  Thinnjeldia  flora,  the  formation  that  is  most  suitable  for  age 
determination  is  undoubtedly  the  Molteno  beds  of  the  Stormberg 
series  of  the  Cape,  because  this  group  fortunately  happens  to  be 
succeeded  by  strata  containing  vertebrate  remains  (saurischian  and 
pseudosuehian)  of  typical  European  Keuper  and  Rhaetic  genera,  and 
its  flora  can  consequently  be  regarded  as  not  younger  than  upper¬ 
most  Keuper. 

Comparisons  of  the  South  African  and  East  Australian  (especially 
the  Ipswich)  assemblages  with  that  of  Argentina  reveal  marked 
resemblances,  which  the  few  published  descriptions  of  the  latter  fail 
to  do  justice  to,  since  many  of  those  determinations  were  based  on 
mere  fragments.  We  find  as  common  species  Thinnfeldia  odontopter- 
oides  (Morr),  T.  lancifolia  (Morr),  and  T.  feistmanteli  John.  ( Cardi - 
opteris  zuberi  Szaj.),  while  certain  large  fronds  from  Cacheuta  placed 
by  Kurtz97  under  T.  lancifolia  are  not  far  removed  from  T.  narra- 
beenensis  Walkom  from  the  Triassic  Hawkesbury  series  of  New  South 
Wales,  and  are  also  very  similar  to  Danxopsis  hughesi  Feist,  a  form 
known  from  the  Stormberg,  Australia,  and  perhaps  Argentina 
(Potrerillos) .  Txniopteris  mareyesiaca  Gein.  is  indistinguishable  from 
T.  dunstani  Walk,  from  Queensland;  T.  brackebushiana  Kurtz  from 
Cacheuta  has  lately  been  identified  in  the  Cape,  while  T.  carruthersi 
and  T.  m'clellandi  (Old.  and  Morr),  known  from  Queensland  and 
Southern  Rhodesia,  have  been  discovered  at  Barreal.  Another  recent 
identification  is  Cladophlebis  goppertiana  (Schen.)  both  at  Barreal 
and  in  Natal  (South  Africa)  the  forms  referred  to  Sphenopteris 
elongata,  and  under  Phcenicopsis  elongata  (Morr)  the  leaves  described 
as  Podozamites  elongatus ,  the  last  two  being  known  from  South  Africa 
and  Australia.  The  form  Chiropteris  copiapensis  Stein,  et  Solms,  from 
La  Ternera  in  Chile  and  from  Cacheuta,  is  also  known  from  the 
Molteno  beds. 

In  addition,  the  widely  distributed  crustacean  Cyzicus  (. Estheria ) 
is  the  same  species  as  originally  described  from  the  Cave  sandstone  of 
South  Africa,  E.  draperi  Jones,  the  associated  smaller  individuals  then 
called  E.  stowiana  being  now  regarded  as  representing  the  youthful 
stage.  The  fish-scales  referred  to  Semionotus  mendozaensis  Gein.  are, 
moreover,  comparable  with  those  of  S.  capensis  S.-Woodw.,  from  the 
Cave  sandstone. 

The  above  comparisons  bring  out  the  great  similarities  in  the 
floras  of  western  Argentina,  the  Cape,  eastern  Australia,  and  Tas¬ 
mania,  apart  from  strong  lithological  resemblances  in  these  beds, 
and  stage  IV  can  accordingly  be  regarded  as  belonging  with  more 
probability  to  the  upper  Triassic  (Keuper)  than  to  the  Rhastic,  in 
which  these  beds  have  hitherto  universally  been  placed.  The  flora  of 
the  Upper  Paganzo  is  quite  different  in  its  composition  from  that  of 

97  Kurtz  (1921-22),  PI.  XIX. 


ARGENTINA  AND  BOLIVIA 


55 


the  undoubtedly  Liassic  flora  with  Otozamites  and  Dictyophyllum 
known  close  at  hand  in  the  upper  part  of  the  Rio  Atuel,  and  differs 
in  several  essentials  from  that  at  La  Ternera,  which,  as  shown  by  the 
marine  fossils  above,  is  almost  certainly  not  earlier  than  Rhaetic.  The 
small  assemblage  described  by  Berry98  from  far  to  the  south  in 
Patagonia,  in  the  Gran  Bajo  de  San  Julian  associated  with  Estheria 
draperi  in  the  upper  part  of  a  thick  mass  of  quartz-porphyry  tuffs 
containing  a  few  coaly  bands,99  displays,  on  the  other  hand,  Liassic 
affinities.  Gothan 1  has  also  expressed  doubt  as  to  whether  the  beds 
at  the  Cerro  Alto  in  Santa  Cruz  that  have  yielded  the  interesting 
cone  of  Araucaria  windhauseni  are  as  low  as  the  Triassic,  as  supposed 
by  Windhausen. 

SECTION  G.  THE  PRE-ANDINE  BELT  OF  NORTHERN  ARGENTINA 

AND  OF  BOLIVIA 

Of  high  importance  are  the  recent  discoveries  pointing  to  a  wide 
distribution  of  the  Permo-Triassic  continental  beds  in  Tucuman, 
Salta,  and  Jujuy,  stretching  into  Bolivia  as  far  to  the  north  as  Santa 
Cruz  at  least  in  the  pre-Andine  chains  bordering  the  plain  of  the 
Gran  Chaco.  The  strata  are  exposed,  for  example,  in  the  various 
ranges,  proceeding  from  south  to  north,  of  the  Sierra  de  Lumbrera, 
Sierra  de  Santa  Barbara,  Sierra  del  Alto,  Sierra  de  Aguaragwe,  Sierra 
de  Mandiyuti,  Sierra  de  Charagua,  and  Sierra  de  Santa  Cruz. 

The  southernmost  outcrops,  seen  a  little  to  the  northeast  of 
Tucuman,  are  separated  by  quite  a  considerable  stretch  of  more 
ancient  rocks  from  the  patches  of  the  equivalent  Paganzo  to  the 
northwest  of  Tinogasta  in  the  Puna  de  Atacama  or  those  of  La  Rioja 
and  Cordoba,  and  there  is  no  actual  connection  between  the  latter 
and  the  “Bermejo  series,  ”  as  this  northern  facies  has  been  named  by 
Heald  and  Mather.2  Nevertheless,  a  few  representatives  of  the 
Gondwana  flora  have  been  found,  while  the  generally  marked  litho¬ 
logical  resemblance  points  to  such  a  correlation.  Further  importance 
attaches  in  that  there  may  be  an  unbroken  succession  right  through 
into  the  Jurassic,  whereas  in  the  rest  of  South  America  almost 
everywhere  either  a  definite  unconformity  or  else  a  pseudo-con¬ 
formity  is  present  at  about  the  top  of  the  Permian  or  near  the  base 
of  the  Triassic. 

The  beds  make  their  appearance  in  a  series  of  narrow  and  often 
faulted  anticlines  from  beneath  tilted  Cretaceous  and  Tertiary,  but 
without  the  intense  crumpling  and  the  igneous  injection  that  charac¬ 
terizes  the  equivalent  formations  to  the  south  and  southwest,  in  which 
structures  at  a  number  of  points  from  Salta  northward  fossiliferous 


98 Berry  (1924). 
"Wichmann  (1922). 


1  Gothan  (1925). 

2 Heald  and  Mather  (1922);  Mather  (1922). 


56  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

shaly  beds,  of  Devonian  age  with  a  typical  austral  marine  fauna, 
form  the  cores.  These  ranges  constitute  the  eastern  Cordillera. 

The  upper  limit  of  the  Bermejo  series,  through  a  distance  of  many 
degrees,  right  up  to  the  northwest  and  west  of  Potosi  in  fact,  is 
formed  by  the  relatively  thin  calcareous  member  with  marine 
fossils — the  “Limestones  and  dolomites  with  Melania  ”  of  D’Orbigny3 
or  the  “Horizonte  Calcareo-Dolomitico”  of  Bonarelli,4  also  called  by 
Heald  and  Mather  the  “Viticua  limestone”  from  the  range  of  that 
name  (lat.  20°.  15'  S.)  and  the  “Cajones  limestone”  in  the  Santa 
Cruz  area. 

This  valuable  datum,  from  5  to  40  meters  thick,  consists  of  white, 
pink,  gray,  or  bluish  hard  limestones  and  dolomites  in  very  regular 
thin  layers,  together  with  chert  in  layers  or  lenses — sometimes 
oolitic — the  rocks  being  much  silicified  in  places.  They  pass  upward 
into  a  group  of  variegated  Keuper-like  marls  with  thin  calcareous 
intercalations,  also  fossiliferous,  up  to  150  meters  in  thickness  in  the 
south.  These  various  limestones  are  characterized  by  the  presence 
of  Chemnitzia  {Melania)  potosiensis  (D’Orb.),  and  have  yielded  a  con¬ 
siderable  fauna,  mainly  gasteropods,  which  Bonarelli  has  shown  to 
point  to  an  uppermost  Triassic  or  Liassic  age.5  The  sandstones  over- 
lying  the  marls  are  apparently  unconformable  and  most  probably  of 
Cretaceous  age. 

Perfectly  conformable  beneath  the  limestone  come  the  uppermost 
sandstones  of  the  Bermejo  series — the  “lower  sandstones”  (arenis- 
cas  inferiores)  of  Bonarelli — but  in  the  Puna  de  Jujuy  the  latter  thin 
out  and  the  limestone,  according  to  Bonarelli,  come  to  rest  either 
directly  or  with  a  thin  basal  conglomerate  on  the  Ordovician,  the 
Devonian  being  absent.6  In  the  Sierra  de  Zapla,  close  to  Jujuy,  the 
Bermejo  is  only  some  400  to  500  meters  thick,  but  more  to  the  north 
it  ranges  generally  from  1,300  to  1,500  meters,  attaining  its  maximum 
of  2,500  meters  in  the  Sierra  del  Alto  (about  lat.  22 0  S.).  While  the 
series  usually  rests  with  unconformity  upon  the  Devonian,  in  certain 
places  no  marked  discordance  has  been  detected  between  it  and  that 
formation  below.7 

Long  ago  D’Orbigny  had  observed  that  over  a  wide  tract  to  the 
northeast  of  the  area  under  consideration,  in  the  neighborhood  of 
Lake  Titicaca,  the  Devonian  was  followed  by  marine  Carboniferous, 
which  has  since  been  proved  over  an  extensive  region  around  Cocha¬ 
bamba  and  also  to  the  southwest  of  Santa  Cruz  on  the  “alt a  planicie  ” 
or  high  plateau  of  Bolivia.  The  fauna,  including  Productus  cora 
D’Orb.,  P.  nebraskensis  Owen,  P.  clarkianus  Derby,  Spirifer  condor 
D’Orb.,  Spiriferina  cristata  Schloth,  Fenestella  retiformis  Schloth,  is 
that  of  the  Uralian  of  the  Urals,  Salt  Range  of  India,  and  Guada- 

3  D’Orbigny  (1842).  6 Bonarelli  (1921),  p.  74;  Jaworski  (1923).  7 Meyer  (1914). 

4 Bonarelli  (1921).  *Ibid.,  p.  21. 


ARGENTINA  AND  BOLIVIA 


57 


lupian  of  New  Mexico,  and  has  species  in  common  with  the  Carboni¬ 
ferous  of  the  Amazon  Valley  and  to  a  less  degree  with  that  of 
the  Sahara. 

On  the  shores  of  Lake  Titicaca,  Douglas 8  observed  red  and  choco¬ 
late  colored  sandstones  and  breccias  following  the  Carboniferous 
limestones  and  shales  conformably,  but  50  km.  to  the  southeast,  at 
Coniri,  the  highest  beds  of  the  former  consist  of  coarse  reddish  con¬ 
glomerates  with  pebbles,  some  of  which  are  of  fossiliferous  Carboni¬ 
ferous  limestone.  These  deeply  colored  rocks  possibly  represent  the 
Bermejo  series.  A  long  distance  to  the  southeast,  not  far  to  the  south¬ 
west  of  Santa  Cruz,  the  undoubted  Bermejo  rests  discordantly  on  the 
arenaceous  “Materal  formation,”  which  is  believed  by  Heald  and 
Mather9  to  be  itself  unconformable  to  the  Devonian  slates,  and  which 
may  perhaps  be  the  continental  facies  of  the  Titicaca  Carboniferous. 

Thus  delimited  above  and  below,  the  Bermejo  is  considered  to 
range  from  the  Permian  to  the  base  of  the  Jurassic,  though,  except 
for  the  mollusca  at  the  top  of  the  series,  the  only  fossils  yet  recorded 
consist  of  Equisetites  and  Phyllotheca  from  Lipeon,  northwest  of 
Oran  in  Argentina,  and  some  Lingulas  from  above  the  glacials  in 
the  Sierra  de  Santa  Cruz. 

Its  lowest  division — the  Oquita  formation10 — is  dominantly  a  gray 
sandstone  followed  by  sandy  shales  and  these  by  cream  or  red  sand¬ 
stones,  or  in  the  Sierra  de  Aguaragwe  by  massive  white  sandstones, 
wThile  the  uppermost  part  is  composed  of  persistent  sandy  shales  of 
various  colors  and  thin-bedded  sandstones.  Certain  shaly  bands  may 
possibly  be  of  glacio-lacustrine  origin,  seen,  for  example,  in  the 
Parapiti  Gorge  (lat.  20°  S.).  The  middle  division  is  the  striking 
Mandiyuti  conglomerate,  which  builds  many  of  the  rugged  cliffs  and 
gives  rise  to  picturesque  scenery.  It  consists  of  massively  bedded 
conglomerate  and  grit,  together  with  sandstones,  and  varies  from 
500  meters  in  the  northern  part  of  the  Sierra  de  Aguaragwe  on  the 
border  of  Argentina  to  1,000  meters  in  the  type  locality  in  the 
Sierra  de  Mandiyuti  farther  to  the  north  (lat.  20°  30'  S.) ;  individual 
beds  as  much  as  80  meters  in  thickness  occur  in  the  midst  of  the 
formation  at  several  localities.  The  majority  of  the  beds  display 
brilliant  shades  of  red  and  purple. 

The  pebbles  in  the  conglomerates  and  grits  are  of  all  sizes  and 
shapes  and  up  to  nearly  a  meter  in  length,  mainly  of  hard  rocks  and 
mostly  well  rounded  and  polished  by  stream  or  current  action,  but  in 
every  locality  are  to  be  found  many  angular  pebbles  with  faceted 
faces,  and  the  deposit  is  therefore  regarded  by  Heald  and  Mather  as 
a  fluvio- glacial  accumulation.  In  the  presumably  equivalent  beds  in 
the  Sierra  de  Santa  Cruz  tough  clays  were  found  carrying  beautifully 

8  Douglas  (1914),  p.  30.  10 Mather  (1922),  p.  739. 

9  Heald  and  Mather  (1922),  p.  560. 


58  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

faceted  grains  and  pebbles,  while  true  tillite  was  also  observed  by 
them.  These  faceted  inclusions  scattered  through  both  the  sand¬ 
stones  and  shales  clearly  indicate  the  presence  of  streams  issuing 
from  a  glacier-front  or  from  glacier-capped  highlands. 

Though  paralleled  by  Heald  and  Mather  with  the  (Carboniferous) 
glacials  of  the  San  Juan-Jachal  area,  it  must  not  be  overlooked  that 
they  may  not  improbably  be  much  higher  in  the  succession,  possibly 
well  up  in  the  Permian,  and  that  they  might  even  be  comparable  with 
the  glacials  of  the  upper  Marine  series  of  the  Hunter  River  area  in 
New  South  Wales  or  perhaps  those  of  the  Congo,  ascribable  to  a 
Triassic  (or  probably  late  Permian)  age  according  to  Ball  and  Shaler. 

The  uppermost  division  of  the  Bermejo  series  ranges  from  250 
to  500  meters  in  thickness,  mainly  massive  soft  green  to  maroon 
sandstones,  with  non-fissile  shales  and  clays  of  red  color,  overlain 
conformably  by  the  “ calcareo-dolomitic  horizon.”  Madgwick  has 
remarked  on  the  highly  false-bedded  nature  of  these  sandstones, 
wherefore  comparison  can  be  instituted  with  the  Rio  do  Rasto  series 
of  the  Santa  Catherina  system  of  Brazil,  the  nearest  occurrences  of 
which  lie  less  than  800  km.  due  east  on  the  railway  from  Porto 
Esperanga  to  Sao  Paulo. 

This  upper  Bermejo  (areniscas  inferiores)  appears  in  the  Cerro 
Colorado,  west  of  Rosario  de  la  Frontera  in  Salta,  beneath  the  lime¬ 
stones  to  a  thickness  of  600  meters  at  least  without  the  base  being 
seen,  yet  in  the  Alto  de  Munoz  and  to  the  south  in  the  Cerro  de 
Campo  this  group  rests  directly  on  the  pre-Cambrian;  clearly  the 
lower  Bermejo  does  not  reach  Salta.11  The  upper  Bermejo,  the  lime¬ 
stones,  and  the  marls  above  together  make  up  the  “formation 
petrollfera”  of  Bonarelli,  in  which  much  boring  has  been  done  at  the 
base  of  the  various  chains. 

That  the  Permo-Triassic  extends  far  to  the  east  beneath  the 
covering  of  Cretaceo-Tertiary  is  indicated  by  the  deep  boring  at 
Alhuampa  previously  mentioned,  in  which  at  a  depth  of  some  1,340 
meters  there  was  cut  a  group  of  dark-reddish  micaceous  sandstones 
and  clays  with  occasional  conglomerates,  down  to  about  1,700  meters 
possibly  Triassic,  and  below  that  down  to  2,111  meters  light  feld- 
spathic  and  micaceous  sandstones  and  grits  with  dark  micaceous 
shales,  which  at  1,860  meters  yielded  impressions  of  Schizoneura  and 
Phyllo theca,  indicating  some  stage  of  the  Paganzo.  It  should  be 
noticed  that  the  volcanic  rocks,  so  well  represented  in  the  Parana 
Basin  and  found  in  borings  just  east  of  the  Parana  River,  and  also  the 
flows  associated  with  Stage  IV  in  La  Rioja,  are  absent  from  the 
northern  belt  just  described. 


11  Stappenbeck  (1921). 


CHAPTER  IV 


PRE-GONDWANA  BASEMENT  OF  EASTERN  SOUTH  AMERICA 

SECTION  H.  THE  DEVONIAN  SYSTEM 

In  all  Brazil  perhaps  the  most  striking  parallel  with  the  Cape  is 
afforded  by  the  central  portion  of  the  State  of  Parana  with  its 
Devono-Gondwana  succession.12  Conspicuous  here  is  the  nearly 
horizontal  Furnas  sandstone,  making  a  belt  curving  from  Faxina  in 
the  north  past  Pirahy,  Castro,  and  Ponta  Grossa  to  Serrinha  with  an 
outcrop  of  fully  300  km.  in  length,  fading  out  at  either  end  beneath 
the  Itarare  glacial  beds.  The  escarpment  that  it  makes  picturesque 
because  of  its  fine  araucarias,  is  known  in  the  north  as  the  Serra  das 
Furnas  and  in  the  south  as  the  Serra  de  Sant’  Anna. 

The  formation,  which  is  perhaps  just  over  150  meters  thick  and 
marvelously  like  the  Table  Mountain  sandstone  of  the  Cape  western 
Province,  rests  on  an  even  surface  cut  equally  across  granite  and 
the  tilted  Assunguy  series,  the  beds  ranging  from  a  white  fine-grained 
sandstone  to  a  coarse  white,  false-bedded  grit  (Plate  XII,  A),  con¬ 
taining  a  little  kaolinized  feldspar  and  tiny  quartz  pebbles,  the  rocks 
giving  rise  to  a  coarse  sandy  soil  and  to  rather  treeless  plains.  Either 
isolated  in  the  sandstone  or  occurring  in  thin  washes  are  pebbles 
up  to  about  7  cm.  in  length,  smooth  and  oval  to  irregular  in  outline 
chiefly  made  of  white  or  flesh-colored  vein-quartz,  together  with  some 
of  quartzites,  and  occasionally  of  cherty  rocks.  At  Ponta  Grossa  I 
observed  none  of  jaspers,  such  as  are  to  be  found  in  the  Clan  william 
district  of  the  Cape,  but  Doctor  Ferraz13  has  ascribed  to  the  Devonian 
certain  coarse  sandstones  with  red  jasper  pebbles  that  cap  the  Morro 
Bahu  to  the  southeast  (860  meters)  not  far  from  the  coast  a  little  to 
the  west  of  Itajahy.  According  to  Leme,14  diamonds  have  been  found 
in  the  sandstones  near  Tibagy,  a  feature  that  has  not  yet  been 
reported  from  the  western  Cape. 

The  concordantly  following  fossiliferous  Ponta  Grossa  shales 
appear  for  a  distance  of  over  200  km.  between  the  Furnas  sandstone 
and  the  overlapping  Itarare  glacials ;  from  the  descriptions  available 
the  highest  zones  are  represented  in  the  central  part  of  the  great  curve 
in  the  neighborhood  of  Tibagy.  At  Ponta  Grossa,  where  nearly  100 
meters  of  these  shales  are  exposed  dipping  gently  beneath  the  Itarare, 
the  strata  recall  down  to  the  minutest  detail  the  lowermost  shale 
group  of  the  Bokkeveld  series  of  the  Cape  western  province  ranging 

12Clarke  (1913),  pp.  36-41;  Woodworth  (1912),  p.  42;  Oliveira  (1925);  Branner 
(1915).  PP-  311-312;  (1919),  P-  288;  Leme  (1924),  pp.  159-162. 

13Ferraz  (1921). 


59 


14  Leme  (1924),  p.  159. 


60  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

from  fine  carbonaceous  shales  with  pyritic  nodules  through  gray  and 
yellowish- weathering  shales  to  soft,  yellowish,  sandy,  and  somewhat 
micaceous  beds;  limestones  are,  furthermore,  absent,  though  hard, 
slightly  calcareous  nodules  containing  Lingulas  are  common.  This 
horizon  has  yielded  abundant  fossils  at  Ponta  Grossa,  Tibagy, 
Jaguariahyva,  etc.,  the  palaeontological  facies  being  closely  com¬ 
parable  with  the  faunal  assemblages  of  the  Bokkeveld,  Falkland 
Islands,  Argentina,  and  Bolivia,  as  detailed  by  Clarke 15  and  Reed 16 
and  summarized  in  Chapter  VI. 

Above  these  beds,  at  Tibagy,  and  overlain  by  some  more  shales, 
is  a  soft,  gray  feldspathie  sandstone — the  Tibagy  Sandstone — up  to 
20  meters  thick,  which  is  characterized  by  casts  of  large  Spirifers, 
and  corresponding  stratigraphically  with  the  well-known  soft,  red- 
weathering  “ f ossilif erous  sandstone”  of  the  Bokkeveld  with  its 
molds  of  Spirifers  and  other  mollusca,  situated  about  130  meters 
above  the  base  of  that  series.  This  is  all  the  more  remarkable, 
because  Reed17  has  just  recently  grouped  the  characteristic  Tibagy 
species,  S.  iheringi,  under  the  name  of  S.  ceres  Reed  var.  iheringi 
Kays,  that  is  so  abundant  in  the  f  ossilif  erous  sandstone  of  the  Hex 
River  Valley  and  Warm  Bokkeveld. 

Except  for  the  fact  that  the  Table  Mountain  sandstone  is  thicker, 
the  lithology  and  succession  in  Parana  compares  almost  exactly  with 
that  of  the  Cape  system  in  the  northeast  of  Clanwilliam,  where  the 
Dwyka  tillite  passes  transgressively  across  the  almost  flat -lying 
Bokkeveld  and  Table  Mountain  sandstone  on  to  the  folded  pre- 
Devonian  slates  and  intrusive  granite. 

Of  note  is  the  recent  discovery  of  such  fossiliferous  shales  and 
sandstones  with  Lingula ,  Orbiculoidea ,  etc.,  in  Uruguay  on  the  Rio 
Negro  at  the  Rincon  de  Alonso  underlying  the  Itarare  glacials;  they 
are  nearly  horizontal.18 

In  Paraguay,  between  60  and  80  km.  to  the  east-northeast  of 
Asuncion,  at  the  Cerro  Aparipi,  and  at  Arroyos  y  Esteros,  Beder  and 
Windhausen19  have  recorded  exposures  of  soft,  medium-grained 
micaceous  sandstones  and  white,  yellow,  or  red  weathered  shales 
with  secondary  limonite ;  these  strata  lie  horizontally  and  must  well 
exceed  70  meters  in  thickness.  To  the  south  they  must  thin  out 
beneath  the  Gondwana  system,  for  in  that  direction  the  latter  come 
to  rest  directly  upon  the  crystallines,  but  the  distance  to  which  they 
extend  toward  the  northeast  is  as  yet  unknown,  that  region  being 
geologically  unexplored.  Windhausen  has  identified  among  forms 
typical  of  the  Ponta  Grossa  shales,  that  characteristic  Hamilton 
brachiopod  Tropidoleptus  carinatus  Conrad,  known  from  the  Erere 


16  Clarke  (1913). 

16  Reed  (1925). 

17 Reed  (1925),  p.  52. 


18  Arocena  (1926),  p.  16. 

19  Beder  and  Windhausen  (1918). 


PRE-GONDWANA  BASEMENT  OF  EASTERN  SOUTH  AMERICA 


61 


sandstone  of  the  Amazon  V alley  and  from  the  Sicasica  beds  of  Bolivia, 
which  accordingly  suggests  a  mid- Devonian  age  and  therefore  a  hori¬ 
zon  somewhat  higher  than  that  present  to  the  east  in  Parana. 

Just  as  on  the  western  so  on  the  northwestern  side  of  the  basin 
the  Devonian  reappears  at  a  point  20  km.  north  of  the  town  of  Rio 
Bonito  not  far  from  Goyaz,  according  to  C.  L.  Baker,20  where  shales 
have  yielded  characteristic  fossils.  Better  known,  however,  is  the 
plateau  of  the  Chapada  in  Matto  Grosso,  overlooking  the  plain  of 
Cuyaba,  wherein  the  Devonian  rests  unconformably  upon  tilted 
slates  and  limestones  of  supposed  Ordovician  age  and  dips  gently 
northward  beneath  Triassic  beds,  the  series  extending  in  that  direc¬ 
tion  toward  Diamante  and  eastward  to  Lagoinha  at  least,  40  km. 
from  Sant’  Anna  de  Chapada.  From  the  remarks  of  Evans,21  Derby, 
Leme,22  and  others  it  would  appear  that  the  great  escarpment  is 
made  by  a  group  of  soft  red  sandstones  with  basal  conglomerates 
followed  by  shaly  beds  with  thin  sandstones.  Smith  puts  the  thick¬ 
ness  of  the  first-named  at  105  meters,  with  the  fossiliferous  shaly  zone 
in  the  next  50  meters,  but  Leme  ascribes  the  value  of  500  meters  to 
the  series,  remarking  that  the  molluscan  fauna  occurs  in  a  ferruginous 
sandstone  in  the  upper  part  of  the  group,  a  statement  seemingly  more 
in  accord  with  the  observations  of  other  visitors.  The  unfossiliferous 
sandstones  below  are  clearly  the  equivalent  of  the  Furnas  sandstone 
and  the  fossiliferous  beds  above  of  the  Pont  a  Grossa  shales. 

The  fossils  described  by  Derby  and  Von  Ammon  have  been 
exhaustively  reviewed  by  Clarke,23  who  points  out  the  great  simi¬ 
larity  of  the  fauna  to  that  of  Parana,  and  to  a  lesser  extent  with  that 
of  Bolivia,  but  contrast  to  the  Maecuru  fauna  of  Amazonas,  and 
remarks  that  the  presence  of  the  uncommon  trilobite  Phacops 
braziliensis  of  boreal  aspect  would  suggest  that  the  Chapada  Devon¬ 
ian,  if  more  closely  studied,  would  disclose  additional  affinities  with 
the  fauna  of  the  Amazon  Valley,  which  in  view  of  its  geographically 
intermediate  position  is  only  to  be  expected. 

A  point  worthy  of  note  is  the  statement  that  the  diamonds  of  this 
region  have  been  concentrated  from  these  Palaeozoic  sandstones  and 
conglomerates.  Scattered  observations  suggest  that  the  Chapada 
Devonian  passes  to  the  northeast  and  east  beneath  the  Triassic  sand¬ 
stones  and  basalts  and  the  Cretaceous  Bauru  sandstones  (‘'sand¬ 
stones  of  the  Taboleiros”  of  Evans),24  and  to  the  northwest  of 
Cuyaba  beneath  the  Matto  shales,  Permian  (?),  while  inliers  to  the 
southwest  in  the  Chiquitos  of  the  Gran  Chaco  form  links  with  the 
Devonian  of  Bolivia. 

An  occurrence  in  Uruguay  is  worthy  of  mention,  though  ascriba- 


20 Baker  (1923),  p.  67, 

21  Evans  (1894). 

22  Leme  (1924),  p.  158. 


23  Clarke  (1913),  pp.  41-46,  p.  148. 

24  Evans  (1894),  p.  98. 


62  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

ble  only  with  doubt  to  the  Devonian,  but,  if  so,  forming  a  link  with 
the  strata  in  the  Sierra  de  la  Ventana.  This  is  the  limited  outcrop 
recorded  by  Walther 25  in  the  neighborhood  of  the  station  of  Piedras 
de  Afilar  on  the  Montevideo-Maldonado  Railway,  and  quite  near  the 
coast.  Resting  with  presumed  unconformity  on  the  granite,  though 
this  is  not  assured,  and  striking  northwestward,  the  beds  make  a 
narrow  strip  with  a  moderately  high  dip  to  the  southwest,  and  give 
rise  to  a  sharp  ridge.  Though  regarded  by  Walther  as  a  faulted-down 
outlier  of  the  Sao  Bento  series,  the  descriptions  of  the  rocks  and  the 
appearance  of  the  latter  in  hand  specimens  incline  me  after  a  dis¬ 
cussion  with  Professor  Walther  to  suggest  a  greater  age  for  the 
strata,  which  consist  mainly  of  a  hard,  fine-grained,  grayish  to 
faintly  greenish  white  quartzite,  together  with  some  hard  reddish 
sandstones.  While  there  is  the  possibility  that  the  beds  may  repre¬ 
sent  a  pre-Devonian  formation,  they  resemble  the  quartzitic  sand¬ 
stones  of  the  Sierra  de  la  Ventana.  On  the  assumption  that  such  is 
the  case,  it  should  be  noted  that  their  strike  is  nearly  parallel  to 
the  course  of  the  “  Gondwanides  ’  ’  within  the  region  to  the  south¬ 
west,  and  hence  at  right  angles  to  the  older  “Brasilides”  to  be  men¬ 
tioned  below. 


SECTION  I.  THE  EARLY  PALAEOZOIC  BEDS 

The  several  terrains  of  early  or  of  pre-Palaeozoic  age,  though 
occupying  great  extents  of  country,  are  surprisingly  little  known, 
and  even  their  relative  ages  are  under  dispute.  Much  discrimination 
will  be  required  in  reading  Branner’s26  account,  for  his  extensive 
areas  classed  under  the  Permian  actually  include  beds  ranging  from 
lower  Palaeozoic  to  late  Cretaceous. 

Prominent  are  the  various  belts  of  pre-Devonian  strata  in  the 
lengthy  stretch  between  the  Rio  de  la  Plata  and  Pernambuco,  of 
which  some  are  probably  of  Ordovician  age,  while  others  may  be 
older.  They,  however,  have  a  general  lithological  resemblance  to  the 
folded  Nama  succession  on  the  eastern  side  of  the  Atlantic,  between 
Cape  Town  and  Luderitz,  and  also  possess  a  strike  that  is  more  or 
less  parallel  to  the  coast.  This  likeness  is  heightened  by  the  fact 
that  in  certain  localities  the  granite  by  which  these  belts  are  flanked 
is  intrusive,  just  as  in  the  Nama  beds  between  Cape  Town  and 
Namaqualand. 

Termed  many  years  ago  the  “Brazilian  system”  by  d’Orbigny, 
this  tectonic  structure  is  most  probably' of  Silurian  age,  extending 
into  eastern  Argentina,  where,  by  no  means  conspicuous,  it  is  crossed 
nearly  at  right  angles  by  the  Permo-Triassic  “Gondwanides”  (see 
Fig.  7)- 

In  Uruguay  these  beds — phy llites,  crystalline  limestones  and 


25Walther  (1919),  p.  10,  p.  77. 


26Branner  (1919). 


PRE-GONDWANA  BASEMENT  OF  EASTERN  SOUTH  AMERICA 


63 


dolomites,  and  quartzites — which  with  great  probability  correspond 
with  those  of  the  Sierra  de  Tandil,  occupy  a  well-marked  belt  com¬ 
mencing  on  the  coast  a  little  to  the  west  of  Maldonado  and  trending 
between  north  and  north-northeast  through  the  departments  of 
Minas,  Treinta  y  Tres,  and  Cerro  Largo,  in  the  last-named  of  which 
they  pass  beneath  the  Gondwana  beds;  within  the  belt  local  devi¬ 
ations  from  the  mean  strike  are  not  unusual.27  Where  I  saw  them  in 
the  Arroyo  Fraile  Muerto,  to  the  southwest  of  Melo,  the  calcareous 
rocks  consisted  of  blue-gray,  fine-grained  limestones  and  brown  and 
sometimes  red-weathering  dolomites  with  subordinate  dark  slates, 
dipping  at  high  angles,  thus  resembling  those  of  the  Nama  system  of 
Namaqualand.  No  fossils  have  yet  been  found  in  them  in  Uruguay.28 

In  southern  Brazil  the  distribution  of  the  limestones  in  the  crys¬ 
talline  complex  is  all  but  unknown  in  Rio  Grande  do  Sul,  though  a 
narrow  belt  possesses,  so  far  as  I  can  gather,  an  easterly  strike  at 
Ca£apava,  but  in  Parana  the  folded  slates,  limestones,  and  quartzites 
of  the  “Assunguy  series,”  veined  and  injected  by  granite  and  quartz- 
porphyry,  have  again  a  northeasterly  strike,  appearing  from  beneath 
the  Furnas  sandstone  near  Curitiba,  near  Castro  at  Iporanga,  and 
below  Xiririca  and  Iguape  in  the  Ribeira  Valley,  and  trending 
through  Sao  Roque  and  Jundiahy  to  the  northwest  of  Sao  Paulo. 
By  the  Brazilian  Geological  Survey  these  beds  have  been  placed 
in  the  Ordovician. 

To  the  northeast  of  the  Sao  Paulo  border  appears  the  similar 
and  apparently  equivalent  “Bambuhy  series”  of  limestones  and 
slates,  which  stretches  in  a  wide  belt  down  the  valley  of  the  Rio  Sao 
Francisco  and  Rio  das  Velhas  to  about  the  thirtieth  parallel.29 
Where  I  saw  this  group  on  the  railway  between  Bello  Horizonte  and 
Pirapora  the  thick  gray  and  black  limestones  were  followed  by  soft 
micaceous  shales  and  flagstones,  the  strata  dipping  usually  at  low  or 
moderate  angles,  though  near  Curvello  they  were  folded  along  twro 
axes  directed  northeast  and  northwest  and  the  slates  displayed  a 
cleavage  and  were  traversed  by  quartz  veins. 

These  beds  were  regarded  by  Branner  as  Permian,  but  Leme  has 
pointed  out  that  they  are  probably  continuous  with  the  strata  at  Bom 
Jesus  de  Lapa  on  the  bank  of  the  Rio  Sao  Francisco  in  the  north,  from 
the  limestones  of  which  Derby  described  Favosites  and  Chastetes. 
The  long-reported  occurrence  of  fossils  in  the  limestones  of  the 
Rio  das  Velhas  and  the  recent  statement  of  the  finding  of  Spirifers 
in  limestone  at  Dores  de  Indaya,  respectively  north  and  northwest  of 
Bello  Horizonte,  and  at  Paracatu  west  of  Pirapora,  as  cited  by  Leme, 
all  point  to  a  Palaeozoic — probably  an  Ordovician  or  Silurian — age  for 

27  Walther  (1919),  pp.  28-38  and  Plate  XV. 

2801iveira  (1918),  p.  8,  (1925);  Leme  (1924),  p.  138. 

29  Leme  (1924),  pp.  139-143. 


64  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

this  extensive  formation  with  general  north-northeasterly  trend.  It 
should  be  noted  that  these  foldings  must  be  of  pre-upper  Carbonifer¬ 
ous  age,  since  the  glacial  beds  at  Areado  in  the  Abaete  Valley  rest 
undisturbed  on  the  tilted  Bambuhy  series. 

North  of  Bello  Horizonte  the  series  must  rest  on  the  granite,  but 
between  Corintho  and  Diamantina  it  is  in  contact  with  and  appears 
to  repose  unconformably  upon  the  ancient  Espina^  or  Cara^a 
quartzites.  It  is  true  that  this  relationship  has  been  called  into 
question,  but  to  my  mind  the  section  seen  in  the  ascent  of  the  Serra 
da  Toccaia  at  Rodeador  Station  clearly  shows  the  quartzites,  here 
bent  into  an  anticline,  passing  beneath  the  gently  inclined  limestones. 

It  is  possible  that  the  strata  in  the  Serra  de  Caetite  and  those 
covering  so  wide  an  area  farther  to  the  northeast  in  Bahia,  such  as 
the  Tombador-Caboclos-Paraguassu  series  described  by  Branner30 
and  Crandall,31  resting  on  granite  or  the  ancient  tilted  Jacobina 
series,  are  the  representatives  of  this  formation.  They  are  bent  into 
open  folds,  with  axes  usually  trending  north-northeast  and  north¬ 
west,  are  overlain  unconformably  by  the  Lavras  series,  and  this  in 
turn  with  probable  disconformity  by  the  Estancia  beds  and  Salitre 
limestones,  which,  as  will  be  shown  in  Section  M,  belong  to  the 
Permo-Carboniferous. 

Immense  interest  attaches  to  the  Lavras  series  of  gray  and  pink 
quartzites  with  conglomerates,  inasmuch  as  they  are  most  definitely 
the  source  of  the  diamonds  and  carbonados  of  Bahia,  with  which  the 
similar  gem-bearing  quartzites  of  Grao  Mogul  in  northern  Minas 
have  been  paralleled.  If  the  stratigraphy  of  this  region  has  cor¬ 
rectly  been  interpreted  in  the  foregoing  account,  then  there  is  a 
strong  probability  that  the  Lavras  series  may  be  of  Devonian  age. 
Branner  has  grouped  it  in  the  Carboniferous,  though  without  palae¬ 
ontological  evidence;  Leme,  on  the  contrary,  emphasizes  the  sig¬ 
nificance  of  the  fact  that  elsewhere  the  diamond  is  known  to  occur  in 
Devonian  sandstones,  namely,  in  Parana  and  the  Chapada. 

SECTION  J.  THE  PRE-CAMBRIAN  FORMATIONS 

A  striking  feature  in  the  geology  of  Minas  Geraes  is  the  long  belt 
of  somewhat  metamorphosed  sediments  called  by  Derby  the  ‘  ‘  Minas 
series,  ”  deposited,  it  is  stated,  unconformably  on  the  granite,  gneiss, 
and  crystalline  schists,  but  complexedly  faulted  and  thrust  by  move¬ 
ments  directed  from  the  east  and  southeast. 

Most  fully  developed  between  Bello  Horizonte  and  Ouro  Preto, 
its  basal  member  is  the  thick  Cara^a  or  Espina^o  quartzite,  which 
forms  the  “backbone”  or  watershed  coursing  northward  through 
Diamantina  and  thence  northeastward  toward  Bahia.  Above  comes 
the  important  “itabirite”  or  iron-ore  formation,  associated  with 

30  Branner  (1910;  1919). 


31  Crandall  (1919). 


PRE-GONDWANA  BASEMENT  OF  EASTERN  SOUTH  AMERICA 


65 


dolomite,  slates,  etc.,  and  followed  by  a  group  of  quartzites.  These 
itabirites  are  identical  with  the  rocks  called  “banded  ironstones,” 
so  marked  a  type  in  the  primitive  systems  of  South  Africa.  In  Bahia, 
according  to  Crandall,  the  Jacobina  series  is  probably  the  repre¬ 
sentative  of  these  rocks  of  Minas. 

Harder  and  Chamberlin32  have  regarded  the  Minas  series  as 
Algonkian,  a  view  which  the  strong  local  metamorphism  fully  justi¬ 
fies;  for  instance,  I  observed  kyanite  in  certain  of  the  highest  beds 
present  at  the  summit  of  the  Itacolumi  Peak  near  Ouro  Preto. 

Because  of  its  alleged  diamondiferous  character,  the  Espina^o 
quartzite  has  by  certain  geologists  been  correlated  with  the  Lavras 
quartzites  of  Grao  Mogul  and  Bahia,  but  there  are  excellent  reasons 
for  concluding  that  the  former  is  a  much  older  formation.  The  alle¬ 
gation  that  the  gem  can  actually  be  traced  up  to  these  quartzites  in 
the  neighborhood  of  Diamantina  is  by  no  means  secure,  several  high 
authorities  having  wholly  denied  this  association.  It  is  true  that 
diamondiferous  gravels  rest  upon  a  peneplain  cut  across  the  quartz¬ 
ites  round  about  Diamantina,  but  the  gems  may  well  have  been 
derived  from  other  sources.  My  examination  of  the  famous  Boa 
Vista  Mine  east  of  Diamantina  showed  most  definitely  that  it  was  an 
eruptive  “pipe”  piercing  the  Espina^  quartzite,  the  gem-bearing 
but  wholly  “non-igneous”  breccia  being  crowded  with  fragments 
derived  from  the  shattering  of  that  formation,  its  somewhat  schistose 
character  proving  the  antiquity  of  this  peculiar  phase  of  volcanicity ; 
not  improbably  its  age  is  pre- Devonian.  Draper’s 33  researches  suggest 
that  several  of  the  other  diamondiferous  occurrences  in  this  part  of 
Brazil  are  of  a  similar  kind. 

It  is  hence  likely  that  the  gems  in  the  Lavras  series  were  in  part 
derived  from  the  waste  of  the  Espina^o  quartzites  because  of  these 
diamond-bearing  pipes.  Again,  it  is  a  matter  of  more  than  ordinary 
interest  that  in  South  Africa  the  diamond  should  be  known  as  a 
detrital  mineral  in  at  least  two  formations  of  “pre-Kimberlite”  age, 
namely,  in  the  “bankets”  of  the  (probably)  pre-Cambrian  Witwaters- 
rand  system  in  the  Transvaal  and  in  the  upper  Triassic  sandstones 
of  Somabula  in  Southern  Rhodesia. 


32  Harder  and  Chamberlin  (1915). 


33  Draper  (1911;  1920;  1921). 


CHAPTER  V 

GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY 

SECTION  K.  THE  PARANA  BASIN 

This  covers  a  region  of  close  on  a  million  square  kilometers,  with¬ 
out  taking  into  account  certain  outliers  to  the  south  and  northwest, 
and  is  therefore  comparable  in  size  with  the  Karroo  “basin”  in 
South  Africa,  but,  in  contrast,  the  volcanic  group  at  the  top  occupies 
a  relatively  much  greater  area. 

Within  this  immense  territory  the  dips  inward  toward  the  north¬ 
east-southwest  axis  are  generally  extremely  slight,  it  being  rare  to 
find  inclinations  of  more  than  about  30.  Two  feeble  cross-ridgings 
athwart  the  basin  run  northwestward  through  Parana  and  Rio 
Grande  do  Sul  respectively,  while  the  base  has  been  brought  down 
to  below  sea-level  at  Torres  on  the  coast.  In  Uruguay,  warping  has 
brought  up  the  basement  granite  inside  the  basin  in  the  Departments 
of  Riviera  and  Cerro  Largo.  On  the  southwest  the  very  flat  syncline 
passes  beneath  the  Neogene  of  the  lower  Parana  along  a  line  that 
runs  rather  regularly  north  and  south. 

Stratigraphy 

Termed  by  I.  C.  White34  the  “Santa  Catherina  system,”  the 
subdivisions  and  their  nomenclature  have  been  altered  from  time  to 
time,  while  a  different  classification  is  employed  by  the  Geological 
Commission  of  Sao  Paulo  to  that  adopted  by  the  Federal  Geological 
Survey  of  Brazil.  I  furthermore  discovered  that  in  Uruguay  the 
classification  used  by  Professor  K.  Walther  and  by  the  State  Boring 
Department  was  still  practically  the  same  as  that  put  forward  by 
White,  but  that  the  boundaries  chosen  for  the  several  subdivisions 
seemingly  did  not  each  fall  at  precisely  the  horizons  adopted  by  the 
Brazilian  Survey.  Such  differences,  however,  are  only  to  be  expected 
with  a  number  of  geologists  laboring  in  an  enormous  territory  inde¬ 
pendent  of  one  another  and  unable  to  meet  and  discuss  essentials 
from  time  to  time.  Attention  is  drawn  to  this  feature,  since  uncer¬ 
tainties  in  the  way  of  exact  correlation  had  arisen  that  I  found  to  be 
due  very  largely  to  such  causes  and  not  to  errors  of  observation 
and  record. 

It  is  regrettable  that  the  Brazilian  Coal  Commission  should  have 
labored  in  an  area  in  which  the  highly  important  basal  glacial  divi¬ 
sion  was  so  feebly  developed,  thus  necessitating  a  revision  in  termin¬ 
ology  for  the  lower  part  of  the  system  at  the  hands  of  Doctor  Oliveira.35 

34  White  (1906),  p.  36.  35 Oliveira  (1918),  pp.  11-12. 

66 


GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY 


67 


I  also  find  it  impossible  to  subscribe  to  the  general  opinion  that  the 
basal  beds  of  the  system  are  so  young  as  Permian  and  am  compelled 
to  place  them  in  the  upper  part  of  the  Carboniferous.  The  strati- 
graphical  break  between  the  Triassic  and  Permian  was  for  a  long 
time  suspected  and  its  recognition  has  come  only  after  comparison 
with  other  parts  of  Gondwanaland  has  indicated  the  presence  of 
such  a  gap  in  the  succession.  The  determination  by  Doctor  Reed 
of  a  Triassic  age  for  the  upper  part  at  least  of  the  Estrada  Nova 
necessitates  a  radical  alteration  in  the  grouping  of  the  beds  and 
further  stratigraphical  investigation  is  now  urgently  needed. 

The  following  classification  is  to  some  extent  tentative  (the 
wavy  line  indicates  an  unconformity  or  stratigraphical  hiatus) : 


Sao  Bento  series  < 


Serra  Geral  eruptives 
Botucatu  sandstone  (where  separable) 
Rio  do  Rasto  group 
Estrada  Nova  (upper  part) 


Rhsetic-Liassic 


►  Triassic 


Passa  Dois  series 


Tuberao  series 


Itarare  series 


)  Estrada  Nova  (lower  part) 
k  Iraty-  group 
[  Palermo  group 
l  Bonito  group 
(Glacial  beds) 


Permian 


>  Upper  Carboniferous 


(1)  The  Succession  at  Fraile  Muerto  in  Uruguay 

Before  entering  into  a  discussion  upon  the  stratigraphy  of  the 
basin,  it  will  be  useful  to  give  some  details  concerning  this  small 
tract  of  country  situated  380  km.  northeast  of  Montevideo,  on  the 
railway  to  Melo,  because  of  the  interesting  stratigraphical  points 
that  can  be  established  there  and  because  of  the  marked  similarity 
in  the  succession  to  that  in  San  Juan  in  Argentina. 

It  was  from  the  upper  part  of  the  Arroyo  Fraile  Muerto,  at 
Laguna  la  Tuna  south  of  the  railway  that  Guillemain36  in  1911  re¬ 
ported  the  presence  of  glacial  beds.  This  area  was  examined  in  more 
detail  by  Walther37  and  described  by  him  in  several  instructive 
writings,  in  which  use  was  made  of  the  important  data  arising  out  of 
borings  made  by  the  Section  de  Perforaciones  of  Uruguay,  mainly 
within  the  stretch  between  the  pre-Gondwana  rocks  forming  the 
Cerro  Largo  on  the  southeast  and  the  railway  from  Fraile  Muerto  to 
Melo  on  the  northwest. 


36  Guillemain  (1911);  also  (1912). 


37  Walther  (1919). 


68  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

On  the  Arroyo  Fraile  Muerto,  at  the  Casa  de  Comereio  belonging 
to  Senor  Gonsalez  (the  Paso  Tla  Lucia),  the  basement  rocks  are 
schistose  greywaekes  evidently  constituting  an  uneven  surface,  over- 
lain  by  pale  sandy  tillite  (lower)  with  finely  striated  boulders  up  to 
80  cm.  in  diameter,  which,  apparently  following  the  contours  of  the 
floor,  is  dipping  gently  northeastward,  succeeded  by  about  1.5  meters 
of  shales — hard,  banded,  and  drab  in  color  at  the  bottom,  and  soft 
and  blue  higher  up,  followed  with  sharp  junction  by  the  upper 
tillite,  a  clayey  material  with  well-striated  boulders  of  fine-grained 
quartzite,  granite,  gneiss,  quartz-porphyry,  phyllite,  limestone,  and 
dolomite,  and  this  in  turn  by  hard  shales,  exposed  along  the  road 
leading  up  to  the  rising  ground  toward  the  east.  This  compound 
tillite  constitutes  th e  first  and  lowest  glacial  horizon. 

The  base  of  the  glacials  is  not  to  be  seen  here,  but  is  exposed 
about  2  km.  farther  downstream,  just  below  the  homestead  of  Paso 
de  la  Cruz,  the  foundation  rocks  consisting  of  highly  tilted  and  folded 
blue-gray  limestones  and  dolomites  with  dark  slaty  bands — probably 
lower  Palaeozoic.  The  floor  is  uneven,  having  been  cut  into  hollows 
that  do  not  always  follow  the  strike  of  the  beds,  but  commonly  the 
direction  of  glaciation,  and  not  improbably  owe  their  origin  to  ice 
action.  The  tillite  is  in  places  tucked  in  beneath  such  low  ridges  and 
at  one  spot  is  banked  up  against  a  vertical  wall  of  limestone,  where 
it  is  crammed  with  lumps  of  that  rock  and  is  furthermore  calcareous 
in  its  matrix  and  rather  hard.  Well-grooved  surfaces  can  be  found 
with  the  striae  directed  north  40 0  west  (true)  and  though  “chatter- 
marks”  were  not  seen,  it  was  noticed  that  on  the  northwestern  side 
of  cross- joints  in  the  pavement  flakes  had  sometimes  been  dislodged, 
leaving  small  gaps  bounded  by  the  vertical  joint  on  the  southeastern 
side,  which  is  sharp-edged,  but  shallowing  out  on  the  northwestern, 
where  the  lip  is  sometimes  weakly  striated.  This,  to  my  mind,  sug¬ 
gests  a  movement  of  the  glacier  toward  the  northwest  rather  than  in 
the  reverse  direction,  which  will  be  observed  to  be  in  agreement  with 
that  deduced  in  Argentina. 

Whereas  the  rock  filling  the  hollows  is  a  tillite  of  normal  charac¬ 
ter,  its  matrix  gets  coarser  on  approaching  the  low  ridges,  and,  when 
overlying  the  latter,  may  become  a  hard,  coarse  grit  with  small 
boulders,  many  of  them  striated,  the  material  arching  over  and 
dipping  at  high  angles  toward  the  tillite  in  the  hollows.  The  phe¬ 
nomena  recall  those  to  be  seen  in  the  ‘  ‘  kames  *  ’  of  the  Pleistocene  glaci¬ 
ation,  wherein  a  glacial  sand  has  become  molded  over  protuberances 
of  the  floor  beneath  the  ice-mass.  The  glacial  beds  are  not  many 
meters  thick  hereabouts,  and  on  passing  upward  the  irregularities 
in  stratification  disappear  and  the  material  grades  upward  into  grits 
and  sandstones  that  are  lying  flat,  though  sometimes  false-bedded, 
and  carry  only  small  pebbles  of  hard  rocks.  Features  just  like  these 


GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY  69 

are  well  known  in  and  have  been  recorded  from  the  “northern” 
Dwyka  of  South  Africa. 

A  few  kilometers  to  the  west,  along  the  railway  at  Cerro  de  las 
Cuentes,  the  basement  complex  displays  typical  roches  moutonnees 
on  which  the  glacials  are  resting,  and  the  sections,  which  I  was 
unable  to  examine  in  detail,  should  well  repay  study. 

Returning  to  the  account  of  the  sections  at  the  Paso  Tia  Lucia, 
the  shales  referred  to  as  overlying  the  first  glacial  horizon  are  suc¬ 
ceeded  to  the  north  by  at  least  1 5  meters  of  grits  with  very  small 
pebbles  and  by  a  bed  of  gritty  stuff  in  which  are  set  boulders  up  to 
75  cm.  across,  well  glaciated,  which  makes  the  second  glacial  horizon. 
The  homestead  of  Senor  Gonsalez  stands  on  this  band,  which,  fol¬ 
lowed  by  a  conspicuous  sandstone,  is  traceable  toward  the  east  up  to 
the  main  road,  a  distance  of  fully  a  kilometer,  while,  according  to  the 
account  given  by  Walther38  a  sandstone  of  this  description  carrying 
boulders  crops  out  between  this  locality  and  Cerro  de  las  Cuentes 
and  plays  an  important  part  in  the  western  end  of  the  Cerro  Largo 
district. 

At  about  20  meters  above  this  glacial  band,  seen  at  several  points 
to  the  east  along  the  ridge  which  the  main  road  to  Fraile  Muerto 
follows  and  finally  passing  below  higher  strata  at  the  Establecimiento 
Quebrachal  to  the  north,  is  the  third  glacial  horizon ,  much  thinner 
and  indicated  only  by  scattered  inclusions  in  the  gritty  sandstones, 
mostly  small  and  composed  of  hard  rock,  some  of  them  certainly  well 
striated;  lumps  of  silicified  wood  are  also  present  in  this  sandstone. 

Sandstones  and  shales  follow  thereon,  all  dipping  northeastward 
at  30  or  40,  giving  a  total  thickness  of  fully  130  meters  of  beds  from 
the  floor  to  a  horizon  where  first  are  seen  the  dark  sandy  but 
“papery”  shales  with  occasional  thin  limestones  and  silicified  wood 
that  continue  to  Fraile  Muerto,  being  well  exposed  in  the  railway 
cutting  to  the  east  of  the  station  and  also  pierced  by  a  bore-hole  in 
the  village  (No.  48)  to  the  depth  of  54  meters. 

These  are  broadly  equivalent  with  the  Iraty  group  and  thus 
furnish  the  datum  plane  from  which  the  stratigraphical  succession 
can  be  determined.  The  130  meters  of  beds  beneath  this  zone  cor¬ 
respond,  therefore,  with  the  Bonito  and  Itarare  of  Brazil,  though  it 
is  impracticable  in  Uruguay  to  draw  a  sharp  line  between  the  two 
divisions,  while  even  the  precise  base  of  the  Iraty  is  a  little  in  doubt. 
I  have  taken  the  latter  at  the  horizon  where  the  highest  of  the  sand¬ 
stones  and  grits  is  to  be  found;  below  that  level  the  strata,  as  dis¬ 
closed  by  borings,  consist  of  white,  fine  to  coarse  sandstones  and 
limonitic  sandstones,  dark  shaly  sandstones,  sandy  shales,  and  some 
bituminous  shales.  All  these  beds  that  lie  above  the  glacials  will  be 
referred  to  in  detail  later  on. 


38  Walther  (1919),  p.  97. 


70  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

(2)  The  Boulder  Beds  in  Brazil 

Proceeding  to  the  consideration  of  the  “ Parana  Basin”  we  find 
the  Itarare  series,  so  called  by  Oliveira,39  consisting  of  a  series  of  beds 
of  glacial  origin,  alternating  with  conglomerates,  grits,  sandstones, 
and  shales  that  are  just  like  those  of  the  succeeding  Bonito  or  Coal 
Measures,  the  first-named  varying  from  unbedded,  true  ground- 
moraine  or  tillite  through  boulder-shale  to  bedded  shale  with  small 
inclusions  and  even  “pelodites”  on  the  one  hand,  and  through 
“sandy”  rocks  with  glacial  erratics  to  sandstones  (sometimes  cross- 
bedded),  with  waterworn  pebbles  (fluvio-glacial  beds)  on  the  other. 
The  succession,  as  well  as  the  relative  proportion  of  “normal”  sedi¬ 
ment  to  glacial  material,  appears  to  vary  in  different  parts  of  the 
country,  just  as  is  true  of  the  Pleistocene  glacial  deposits  of  the 
Northern  Hemisphere,  and,  while  in  places  the  top  of  the  group  is 
sharply  defined,  as,  for  example,  to  the  northwest  of  Jaguariahyva 
in  Parana,  the  upper  limit  is  commonly  vague,  the  chief  criterion 
being  the  absence  higher  up  of  any  pebbly  bands  displaying  charac¬ 
ters  not  purely  fluviatile.  It  is  obvious  that  in  borings  the  upper 
limit  of  the  Itarare  would  often  be  rather  indefinite,  just  as  is  the 
case  in  Uruguay,  while  certain  conglomeratic  strata  at  present 
mapped  with  the  Bonito  may  in  the  future  be  found  to  be  of  fluvio- 
glacial  origin  and  therefore  have  to  be  placed  with  the  Itarare. 

The  northeasternmost  point  from  which  this  series  has  been 
reported  is  in  the  Abaete  Valley  in  Minas  Geraes,  where,  according 
to  Rimann,40  the  glacials  and  the  succeeding  “Areado  sandstone” 
rest  upon  the  tilted  lower  Palaeozoic  Bambuhy  series,  the  existence 
of  the  tillite  in  that  neighborhood  having  long  previously  been  noted 
by  D.  Draper.41  This  area  is  not  improbably  an  outlier  from  the 
main  basin,  for  to  the  west,  so  far  as  can  be  gathered,  the  Triassic 
sandstone  rests  directly  upon  mica- schists  at  the  Agua  Suja  diamond 
mine,  and  on  granite  between  Sacramento  and  Franca.  The  tillite 
appears  more  to  the  south  near  Mococa,  is  relatively  thin  at  Monte 
Santo,  and  runs  in  a  widening  belt  southward  through  Casa  Branca 
past  Campinas  and  Sorocaba,  at  the  same  time  becoming  thicker. 
Excellent  descriptions  have  been  given  by  Woodworth42  and  Cole¬ 
man  43  of  the  glacials  in  the  region  both  to  the  northwest  and  west  of 
Campinas,  while  a  fine  photograph  of  the  boulder-beds  has  been 
reproduced  by  Branner.44 

From  Sorocaba  the  belt  curves  south  west  ward  to  Tibagy  and 
then  turns  abruptly  southeastward  past  Ponta  Grossa,  Serrinha,  Rio 
Negro,  and  onward,  the  group  ranging  in  thickness  from  250  to  350 
meters  in  Parana,  but  becoming  progressively  thinner  in  the  direc- 

39  Oliveira  (1918),  p.  12.  42  Woodworth  (1912). 

40Leme  (1924),  p.  178.  43 Coleman  (1918), "pp.  312-317;  (1926),  pp.  156-162. 

41  Branner  (1919),  p.  214.  ,  44  Branner  (1919),  PI.  X. 


GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY 


71 


tion  of  Santa  Catherina.  Woodworth’s45  detailed  section  of  the 
group  between  Itaicy  and  Piracicaba  shows  a  huge  development — 
between  700  and  1,000  meters,  mainly  of  sandy  tillite  and  sandstone, 
with  at  least  two  important  partings  of  shales,  although  much  of  the 
material  can  not  strictly  be  referred  to  as  tillite,  consisting  as  it  does 
of  sandstones  with  occasional  small  boulders,  while  similar  erratics 
occur  in  certain  of  the  shaly  bands.  The  succession  is  consequently 
rather  like  that  described  by  various  geologists  at  Bacchus  Marsh  in 
Victoria,  though  fossils  have  not  yet  been  recorded  therefrom. 

The  accounts  by  Woodworth  and  by  Coleman  of  the  glacials  at 
Jaguaricatu,  Sengens,  Itarare,  and  Ponta  Grossa  give  a  very  good 
idea  of  the  variable  nature  of  the  deposits,  but  much  of  the  rock, 
when  fresh,  is  actually  a  dark-blue  massive  tillite,  often  weathering 
spheroidally,  with  rather  small  inclusions,  though  at  times  boulders 
of  over  a  meter  across  can  be  seen ;  the  rock  thus  recalls  the  Dwyka 
conglomerate.  From  near  the  railway  station  of  Elias  Fausto,  Doctor 
Pacheco  has  reported  some  unusually  large  granite  erratics,  one  of 
them  measuring  fully  3  by  3  by  2  meters.  The  material  at  Ponta 
Grossa,  on  the  contrary,  I  found  to  be  a  yellowish  soft  sandstone 
with  only  a  few  conglomeratic  bands  in  which  striated  stones  are 
decidedly  rare.  Boulder  beds  in  verity  with  abundant  and  large 
inclusions  were,  however,  observed  between  Rio  Negro  and  Campo 
do  Tenente  on  the  railway  to  Serrinha. 

Whereas  the  floor  beneath  the  Itarare  is,  so  far  as  can  be  gathered, 
rather  even  in  the  States  of  Sao  Paulo  and  Parana,  the  features 
visible  at  Serrinha  and  the  description  given  of  the  glacials  there  by 
Woodworth46  indicate  an  irregular  floor  and  indeed  suggest  to  me  the 
presence  of  a  “pre-glacial”  gorge  in  the  Furnas  sandstone,  cut  right 
down  into  the  pre-Devonian  slates  beneath,  the  northern  wall  of 
which  is  made  by  the  sandstone  cliffs  a  few  hundreds  of  meters  from 
Serrinha,  along  the  railway  to  Curitiba,  the  hollow  being  filled  in 
with  a  sandy  tillite  overlain  by  a  fluvio-glacial  sand.  The  general 
aspect  strongly  reminds  me  of  several  well-established  cases  of  such 
a  kind  in  Natal  (South  Africa),  where  the  Dwyka  tillite  is  resting 
in  ravines  cut  in  the  Table  Mountain  sandstone  and  in  places  lies 
banked  against  cliffs  of  the  latter,  for  example,  on  the  Umtamvuna 
River  near  the  road  bridge  between  Izingolweni  and  Bizana.  The 
high  irregularity  of  the  pre-glacial  landscape  is,  moreover,  obvious 
between  Serrinha  and  Lapa,  a  little  distance  to  the  south. 

The  sections  between  Rio  Negro  and  Canivete  on  the  Porto 
Uniao  Railway  reminded  me  very  much  of  the  Dwyka  in  parts  of 
Natal  and  Zululand — the  blue,  solid  tillite,  blue  uniform  mudstone 

L 

with  hardly  any  stratification,  and  bedded  blue  shales.  The  latter, 
in  thickness  from  a  few  decimeters  upward,  run  regularly  for  good 

45  Woodworth  (1912),  pp.  54-61.  46  Ibid.,  pp.  65-66. 


72  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

distances  and  probably  mark,  just  as  they  do  in  Natal,  the  temporary 
cessation  of  morainic  deposition  within  an  estuary,  but  opportunity 
for  detailed  examination  was  wanting.  The  discovery  by  Doctor 
Oliveira  of  marine  fossils  close  to  Teixeira  Soares  on  the  railway 
southwest  of  Ponta  Grossa  and  again  at  Rio  Negro  in  black  shales 
sandwiched  between  two  banks  of  boulder  shales — so  far  as  I  can 
gather  in  the  upper  part  of  the  Itarare — indicates  that  the  ice  was  at 
a  certain  stage  discharging  into  the  ocean,  just  as  was  the  case  with 
the  Dwyka  ice-cap  between  Keetmanshoop  and  Mariental  in  the 
Warmbad  district  in  Southwest  Africa.  The  fossils,  which  are  as  yet 
undescribed,  consist  of  small  forms  of  Lingula ,  Discina ,  Leda  (?),  a 
pentamerid  brachiopod,  a  gasteropod  resembling  Pleurotomaria, 
other  indeterminable  forms,  scales  of  ganoid  fishes,  and  wings  of 
insects.47 

To  the  south  of  Rio  Negro  the  Itarare  is  still  thick — over  270 
meters  on  the  Lages-Florianopolis  road — though  there  it  includes 
152  meters  of  beds  at  the  base  doubtfully  grouped  with  the  Gon- 
dwana,  but  regarded  by  Oliveira  as  forming  an  integral  part  thereof. 
Approaching  the  Tuber ao  Valley  the  Itarare  must  thin  rapidly,  being 
there  represented  by  32  meters  of  strata,  of  which  the  well-known 
massive  “Orleans  conglomerate”  forms  the  bulk,  a  stratum  in  which 
the  pebbles  are  sometimes  from  20  to  25  cm.  in  diameter,  and  perhaps 
only  a  local  deposit.  Some  2  km.  below  the  station  of  Lauro  Muller, 
resting  directly  on  granite,  are  shales  enveloping  a  large  granite 
erratic  which  is  in  contact  with  the  floor,  as  figured  by  both  White48 
and  Woodworth.49  From  this  point  the  boundary  with  the  granite 
runs  southward  past  Cocal  and  the  group  ends  near  the  mouth  of 
the  Urussanga  River. 

In  Rio  Grande  do  Sul,  the  Itarare  is  thin  or  missing  between 
Porto  Alegre  and  the  Uruguayan  border.  In  the  Gravatahy  coal¬ 
field  a  little  to  northeast  of  Porto  Alegre,  according  to  data  kindly 
supplied  me  by  Doctor  Simch,  the  bore-holes  pass  directly  through 
shales  and  clays  belonging  to  the  Bonito  into  granite,  which  indi¬ 
cates  the  overlapping  of  the  higher  group  on  to  the  Carboniferous  floor. 
Due  west  of  Porto  Alegre,  between  Xarqueadas  and  Butia,50  a  basal 
conglomerate  is  erratically  developed,  resting  on  granite  and  con¬ 
taining  large  blocks  of  that  rock;  important  is  the  section  revealed 
by  the  old  Isabel  shaft  near  Sao  Jeronymo,  where  the  42  meters  of 
beds  referred  to  as  the  “Orleans  conglomerate” 51  include  shales, 
some  of  them  dark  and  bituminous.  Between  Suspiro  and  Jaguary,52 
on  the  Cacequy-Rlo  Grande  Railway,  an  unbedded  gray  shaly  rock 
1  meter  thick  with  inclusions  resting  on  the  granite  probably  alone 

60  White  (1908),  pp.  43,  47. 

51  Ibid.,  p.  1 19. 

62  Oliveira  (1918),  p.  27. 


47  Oliveira  (1918),  p.  14. 

48  White  (1908),  plate  facing  p.  28. 

49  Woodworth  (1912),  Fig.  23. 


GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY 


73 


represents  the  glacials,  being  overlain  by  conglomeratic  sandstones, 
sandstones,  shales,  and  coals — the  Bonito  beds. 

(3)  The  Boulder  Beds  in  Uruguay 

The  distribution  of  the  boulder  beds  in  Uruguay  is  hardly  known, 
except  in  the  vicinity  of  Fraile  Muerto,  as  described  above  in  (i), 
but  there  can  be  no  doubt  as  to  the  highly  diversified  character  of 
the  “pre-glacial”  surface  in  northeastern  Uruguay.  While  the  dip 
of  the  formations  is  everywhere  low,  knobs  of  the  crystalline  floor 
project  through  the  covering  of  Gondwana  beds  at  a  number  of  places, 
the  surrounding  strata  being  formed  in  some  instances  by  the 
Estrada  Nova  even.  Such  a  granite  inlier  occurs  along  a  tributary  of 
the  Arroyo  del  Chuy,  north-northeast  of  Melo,  one  just  to  the  east 
of  that  town,  another  to  the  south,  forming  the  Cerro  Verde,  and  two 
in  the  Arroyo  Quebrebracho  to  the  northwest  of  the  station  of  Cerro 
de  las  Cuentas.  The  conspicuous  Cuchilla  de  Cerro  Largo  has  all  the 
appearance  of  being  a  glaciated  range  that  must  have  remained 
exposed  long  after  the  ice  had  disappeared  and  its  undulating  base 
had  become  buried  beneath  glacial,  fluvio-glacial,  and  normal 
sediments. 

The  bore-hole  of  Zanja  Honda,  situated  in  the  valley  on  the  north¬ 
western  side  of  this  great  ridge,  passed  down  into  phyllites  at  about 
70  meters,  the  section  showing  several  meters  of  blue-gray  conglom¬ 
erate  and  breccia,  which  from  the  cores  preserved  I  believe  to  be  of 
glacial  origin,  overlain  by  14.8  meters  of  sandstones  and  these  by 
12  meters  of  the  curious  banded  shales  described  by  Walther53  under 
Woodworth’s  name  of  “  desmopelodite,  ”  and  which,  from  their 
alternating  light  and  dark  laminae  of  differing  texture  (in  thickness 
from  12  down  to  below  1  mm.),  have  been  compared  with  the 
seasonally  banded  glacial  clays  of  the  Pleistocene.  Similar  beds  were 
described  by  Guillemain  at  Laguna  la  Tuna  in  the  head  of  the 
Arroyo  Fraile  Muerto,  which  not  improbably  correspond  with  the 
“inter-glacial”  shale  parting  in  the  lowest  glacial  horizon  at  Paso 
Tia  Lucia  a  short  distance  farther  down  the  valley.  These  shales  were 
obviously  laid  down  in  tranquil  water  (limno-glacial  deposits)  and 
display  on  their  faces  what  are  supposed  to  be  crustacean  tracks.  If 
the  33  meters  of  strata  at  Zanja  Honda  immediately  above  them 
represent  the  Iraty,  as  stated  by  Walther,  though  this  with  good 
reason  is  doubted  by  Arocena,54  then  a  great  overlap  has  taken  place 
within  a  distance  of  25  km.  with  the  suppression  of  the  Bonito,  which, 
taking  into  account  the  physiographical  conditions  that  must  have 
been  present,  would  not  be  altogether  unexpected. 

While  Walther ’s  account55  shows  that  coarse  sandstones  with 

53  Walther  (1919),  p.  91  and  PI.  X.  65  Walther  (1919),  pp.  97-98. 

54  Arocena  (1926),  p.  5. 


74  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

boulders,  possibly  the  second  glacial  horizon,  play  an  important  role 
to  the  west  of  Cerro  de  las  Cuentas,  so  far  west  indeed  as  the  Arroyo 
Cordobes,  and  while  glacials  have  recently  been  discovered  in  the 
region  immediately  beyond,  it  would  appear  that  a  little  to  the  north 
of  Durazno  the  Triassic  has  overstepped  the  lower  series.  As  regards 
the  deep  boring  at  Tacuarembo,59  it  is  just  possible  that  glacial  beds 
here  form  an  important  group,  my  examination  of  the  cores  showing 
that  from  310  meters  downward  they  are  perhaps  as  much  as  40 
meters  thick,  including  a  dark  gray  clayey  rock  and  a  pale  gray  gritty 
material  with  grains  of  quartz  and  rock  fragments,  passing  down  at 
about  349  meters  into  a  typical  tillite  containing  pebbles  of  granite 
with  the  granitic  basement  struck  at  about  350  meters.  No  similar 
rocks  have  yet  been  noticed  at  the  base  of  the  system  shortly  toward 
the  east  along  the  Tacuarembo  River,  where  again  the  Triassic 
appears  to  transgress  on  to  the  basement.60 

It  is  unfortunate  that  so  little  should  be  known  about  the  north¬ 
western  side  of  the  Parana  Basin.  No  glacials  have  yet  been  reported 
from  Paraguay  or  southern  Matto  Grosso,  though  they  are  known  to 
occur  close  to  Rio  Bonito  in  the  southern  part  of  Goyaz,  resting 
apparently  on  the  Devonian,  and  not  unlikely  are  present  in  the 
upper  part  of  the  Parnahyba  Valley  also. 

(4)  The  Position  of  the  Glacial  Center 

Although  the  rounded  granite  surfaces  recorded  close  to  Campi¬ 
nas  in  Sao  Paulo  do  not  bear  any  definite  striae,  and  roches  moutonnies 
have  not  been  recorded  elsewhere  in  Brazil,  a  certain  amount  can  be 
deduced  regarding  the  probable  position  of  the  Carboniferous  glacial 
center  from  the  inclusions  in  the  tillite  of  Sao  Paulo  and  Parana. 
Coleman 61  has  mentioned  erratics  of  a  peculiar  coarse  conglomerate 
near  Capivary  containing  pebbles  of  brilliant  red  jasper  derived  from 
some  ancient  formation  unknown  in  the  country,  and  which  I  have 
elsewhere  remarked  are  very  like  those  found  in  the  Dwyka  of 
Southwest  Africa  that  must  have  been  derived  from  the  Matsap 
series  of  Griqualand  West  lying  hundreds  of  kilometers  to  the  east. 
Recently,  however,  Dr.  L.  C.  Ferraz 62  has  recorded  a  practically 
identical  conglomerate  in  situ  far  to  the  south,  in  the  Morro  Bahu, 
on  the  north  side  of  the  Itajahy  River  close  to  Blumenau,  in  Santa 
Catherina,  which,  if  not  the  source  of  the  blocks  in  question,  would 
indicate  at  least  the  likelihood  of  a  southerly  origin. 

Furthermore,  Woodworth63  has  drawn  attention  to  certain  inclu¬ 
sions  of  fine-grained  white  sandstone  (whetstone),  which  are  indica¬ 
tive  of  an  easterly  derivation.  In  Uruguay,  as  has  been  pointed  out, 
the  center  seemingly  lay  toward  the  southeast,  and  a  similar  direc- 

69  Walther  (1919),  p.  100.  61  Coleman  (1918),  p.  314.  63  Woodworth  (1912),  p.  63. 

60Arocena  (1926).  62 Ferraz  (1921).  •  . 


GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY 


75 


tion  is  prompted  by  the  Argentine  occurrences,  all  of  which  suggest 
an  area  lying  out  in  the  present  Atlantic,  and  with  which  the  sporadic 
development  of  the  glacials  and  the  overlapping  of  the  higher  beds  on 
to  the  crystallines  in  the  extreme  south  of  Brazil  would  appear  to 
support.  A  certain  amount  of  speculation  on  this  problem  will  be 
indulged  in  later  on. 

(5)  The  Tuberao  Series 

Doctor  Oliveira  has  restricted  the  name  Tuberao  series  to  the 
strata  above  the  Orleans  conglomerate  or  the  Itarare  glacials, 
namely,  to  the  Bonito  group  below  and  the  Palermo  group  above,  the 
former  about  180  meters  thick,  the  latter  about  80  meters,  or  270 
meters  in  all. 

The  Bonito  consists  of  soft,  yellowish  and  grayish-white  sand¬ 
stones,  sometimes  in  massive  beds,  interbedded  with  bluish  or  gray 
and  occasionally  micaceous  shales,  often  plant-bearing;  conglomer¬ 
ates  are  rare  and  thin.  Important  is  the  occurrence  therein  in  Brazil 
of  seams  of  coal  upon  at  least  five  horizons  that  are  identifiable  over 
pretty  wide  areas.  The  workable  seams  are  those  of  the  Bonito  coal 
about  midway  in  the  succession  and  the  Barro  Branco  or  Sao  Jero- 
nymo  coal  near  the  top ;  partings  of  shale  are  general,  and  the  coals 
are  always  high  in  ash  and  often  extremely  pyritic.  They  are  well 
developed  in  the  Tuber ao-Treviso  area  in  Santa  Catherina  and  again 
along  the  Jacuhy  Valley  west  of  Porto  Alegre  in  Rio  Grande  do  Sul, 
while  coals  have  also  been  proved  at  intervals  on  the  Rio  Grande 
Railway,  such  as  at  Suspiro,  Rio  Negro,  Candiota,  and  between 
Cerro  Chato  and  Sao  Jo ao  do  Herval  down  to  the  Uruguayan  border, 
and  also  in  the  opposite  direction  in  the  belt  west  of  Ponta  Grossa  and 
Tibagy  in  Parana  and  on  the  Rio  das  Cinzas  northwest  of  Itarare. 
A  wealth  of  detail  is  to  be  found  in  the  monumental  report  of  the 
Brazilian  Coal  Commission64  and  in  the  supplementary  memoir 
by  Doctor  Oliveira.65 

The  Palermo  group  is  formed  mainly  of  soft  shaly  beds  of  a  gray 
or  blue  color  (though  red  tints  have  occasionally  been  observed  in 
Parana)  and  passes  up  without  a  break  into  the  Iraty  shales.  It  is 
marked  off  from  the  Bonito  in  Brazil  by  a  calcareous  horizon  with 
large  nodules  of  chert,  while  silicified  wood  of  the  genus  Dadoxylon 
is  common,  but  the  group  is  difficult  to  delimit  in  Uruguay. 

It  might  be  noted  that  in  two  areas  where  coals  are  locally 
developed  in  the  basal  part  of  the  Bonito,66  a  thin  seam  rests  directly 
upon  the  top  of  the  tillite  forming  part  of  the  Itarare,  for  example,  in 
the  valley  of  the  Rio  das  Cinzas  and  at  Butia  to  the  southwest  of  Sao 
Jeronymo,  and  seemingly  also  near  Suspiro  on  the  Rio  Grande  Rail¬ 
way,  thus  recalling  to  some  extent  the  features  to  be  seen  at  Vereenig- 

66  Oliveira  (1918).  66  Ibid.,  pp.  34,  103. 


64  White  (1908). 


76  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

ing  in  the  Transvaal,  where  the  Ecca  coals  may  rest  directly  upon 
either  tillite  or  pre- Devonian  dolomite. 

It  is  further  interesting  to  observe  that  the  Tuber ao  series,  when 
followed  northward  into  the  State  of  Sao  Paulo,  where  it  is  termed 
the  “Tatuhy  ”  by  Doctor  Pacheco,  is  largely  made  by  greenish  sand¬ 
stones,  and  that  coals  are  absent,  save  for  a  seam  at  Jacuha,  20  km. 
southwest  of  Campinas,  overlain  by  a  boulder  bed  supposed  by  him 
to  be  of  glacial  origin,  but  which  is  supposed  by  others  to  be  remanie, 
as  in  the  succession  at  Vereeniging.  Between  Limeira  and  Rio 
Claro,  in  Sao  Paulo,  the  Tatuhy,  followed  by  the  Iraty,  has  become 
quite  thin. 

In  the  opposite  direction  the  Gondwana  beds  make  a  basin  near 
the  Uruguayan  border  and  the  Tuber  ao  is  found  to  the  south  of  the 
Jaguarao  River,67  where,  in  three  bore-holes  at  least,  92  meters  of 
beds  were  proved  beneath  the  Iraty  group  with  Mesosaurus ,  dis¬ 
closing  a  seam  of  impure  coal  1  meter  thick  that  probably  corresponds 
to  one  of  the  upper  coals  of  this  series  in  Brazil.  This  being  the  first 
locality  in  Uruguay  where  coal  was  struck,  borings  were  thereafter 
undertaken  at  a  number  of  points  in  the  Department  of  Cerro  Largo 
and  also  at  Tacuarembo — the  sections  of  which  have  been  detailed 
by  Walther68 — but  without  success,  from  which  it  would  appear 
that  the  limit  of  the  area  characterized  by  the  coal-bearing  facies  of 
the  lower  Gondwana  has  been  reached  somewhere  about  Melo, 
though  I  am  inclined  to  agree  with  Walther  that  the  borings  at 
Buena  Vista  and  Isla  de  Zapata  were  stopped  too  soon.  The  boring 
in  the  town  of  Melo  showed  no  less  than  301  meters  of  strata  ascri- 
bable  to  the  Tuberao  without  the  crystalline  floor  being  reached, 
though  it  is  not  improbable  that  toward  its  base  fluvio-glacial  beds 
like  those  described  from  Fraile  Muerto  were  actually  cut. 

It  is  undoubted  that  to  the  southwest  of  Melo  the  thickness  of 
strata  decreases  considerably,  which  is  in  great  part  due  to  the 
uneven  character  of  the  floor  upon  which  the  beds  repose,  as  proved 
by  the  isolated  inliers  of  granite  in  the  midst  of  the  nearly  horizontal 
sediments,  as  already  referred  to.  The  equivalent  of  the  Palermo  is 
more  arenaceous  than  in  the  coal-fields  of  Brazil,  making  it  practic¬ 
ally  impossible  to  separate  this  group  from  the  Bonito.  The  same  is 
the  case  to  the  west,  the  Tacuarembo  boring  exhibiting  only  84 
meters  of  strata  between  the  Iraty  and  the  granite,  of  which  perhaps 
only  just  over  one-half  can  be  relegated  to  the  Tuberao  (Bonito 
and  Palermo). 

Westward  in  Argentina  the  Bonito  is  apparently  represented  in 
the  San  Cristobal  bore-hole  in  Santa  Fe  at  between  1,140  and  1,384 
meters,  some  of  the  sandstones  being  reddish,  like  the  Paganzo,  a 
feature  still  more  marked  in  the  Tostado  bore-hole  (1,600  meters)  to 

67  Walther  (1919),  pp.  92-93.  68  Ilid.,  pp.  99,  100;  see  also  (1924). 


GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY  77 

the  northwest,  but  the  strata  in  the  Alhuampa  bore-hole,  from  1,700 
meters  down  to  2,100  meters,  are  whiter  again. 

Our  knowledge  concerning  this  series  on  the  northwest  and  north 
of  the  basin  is  of  the  scantiest.  Information  given  me  by  Doctor 
Beder  and  an  examination  of  the  specimens  collected  by  him  in 
Paraguay  show  that  carbonaceous  shales  occur  about  Santa  Maria  to 
the  west-northwest  of  Posadas  and  grits,  sandstones,  conglomerates, 
and  carbonaceous  shales  like  those  of  the  Bonito  at  Paraguary  close 
to  Asuncion  and  similar  strata  at  Villa  Hayes,  a  little  above  that 
town,  on  the  right  bank  of  the  Paraguay  River,  the  latter  consti¬ 
tuting  the  only  solid  rock  exposed  in  the  broad  alluvial  plain  west  of 
that  river. 

(6)  The  Flora  of  the  Bonito  Group 

D.  White 69  and  G.  Lundqvist 70  have  materially  added  to  Zeiller’s 
original  description,  while  the  former  has  also  made  it  clear  that  the 
plants  occur  on  various  levels  from  almost  immediately  above  the 
Orleans  conglomerate  upward.  Those  from  the  lower  part  of  the 
group  in  striking  fashion  consist  solely  of  typical  members  of 
the  southern  flora,  such  as  Gangamopteris  cyclopteroides  {G.  obovata 
White),  Glossopteris  browniana,  Cordaites  hislopi ,  Phyllotheca  gries- 
bachi  and  P.  muelleriana,  but  on  a  higher  horizon  in  association  with 
Glossopteris  indica,  G.  ampla ,  G.  occidentals,  and  on  some  unknown 
level  Neuropteridium  validum  and  Annularia  australis,  appear 
Lepidophloios  laricinus,  Sigillaria  brardii,  Lepidodendron  pedro- 
anum,  Sphenophyllum  oblongifolium,  Pecopteris  spp.,  and  perhaps 
Lycopodiopsis  derbyi,  though  the  last  is  regarded  by  White  as  a 
southern  form. 

It  is  instructive  to  observe  that  in  western  Argentina  these  latter, 
as  well  as  other  northern  Carboniferous  forms,  appear  to  have  been 
found,  together  with  the  southern  types,  in  the  lowest  stage  of  the 
Paganzo,  so  that  in  Brazil  these  “exotic”  forms  make  their  entry  at 
a  somewhat  later  date  apparently.  In  South  Africa  they  entered  at 
a  later  period  still  during  the  Ecca,  subsequent  indeed  to  the  deposi¬ 
tion  of  the  Iraty  group.  It  is  to  be  hoped  that  further  systematic 
collecting  may  be  undertaken  to  afford  additional  information  on  this 
important  question.  These  observations  rather  lessen  the  probability 
of  White’s 71  supposition  that  those  northern  forms  were  able  to  pene¬ 
trate  the  region  only  because  of  a  progressive  amelioration  of 
the  climate. 

In  making  age  determinations  we  have  to  eliminate  the  prepond¬ 
erant  southern  element  as  being  of  no  direct  value,  though  of  course 
that  assemblage  is  closely  related  to  the  floras  of  the  equivalent 
Talchir-Karharbari  series  of  India,  the  Greta  Coal  Measures  of  New 

69  White  (1908),  pp.  361-373;  also  (1907),  p.  617.  71  White  (1908)^.399. 

70  Lundqvist  (1919). 


78  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

South  Wales,  and  the  Ecca  Coal  Measures  of  South  Africa.  Con¬ 
sidering  merely  the  northern  forms,  the  five  just  mentioned,  together 
with  Samaropsis  {Car diocar port)  bar  cello  sa  are  all  identical  with  or 
very  closely  related  to  typically  upper  Carboniferous  species ,  and  in 
my  opinion  form  useful  confirmation  for  a  pre-Permian  age,  such  as 
has  been  arrived  at  from  other  considerations,  though  this  view 
differs  radically  from  the  conclusions  reached  by  D.  White  and 
certain  others. 

(7)  The  Passa  Dois  Series 

This  embraces  the  Iraty,  some  70  meters  thick,  below',  and  the 
Estrada  Nova  (or  Corumbatahy) ,  fully  150  meters  thick,  above,  two 
groups  that  are  extraordinarily  constant  throughout  the  basin, 
though  not  yet  recognized  in  central  or  western  Argentina. 

The  Iraty  group 72  is  composed  chiefly  of  black,  carbonaceous,  and 
often  “papery”  shales,  in  places  pyritic,  and  which  on  being  freshly 
broken  may  give  out  an  odor  of  petroleum ;  small  veins  of  bituminous 
matter — albertite  or  grahamite — are  sometimes  to  be  found.  On 
weathering  they  bleach  to  pale  bluish,  and  finally  to  white  or  faintly 
pink,  flaky  clay  shales  with  secondary  gypsum,  exactly  as  in  the  case 
of  the  “White  band  ”  of  the  Dwyka  shales.  Characteristic  are  nodules 
of  chert  and  thin  layers  of  limestone  (particularly  toward  the  base), 
sometimes  fibrous  in  structure. 

In  Uruguay  the  shales  are  not  so  argillaceous,  while  thin  bands  of 
white  sandstone  and  darker  micaceous  sandstone  are  also  present, 
making  it  difficult  to  delimit  the  group  from  the  “Palermo  ”  beneath, 
which  fact  explains  the  excessive  value  given  by  Walther  for  its 
thickness,  though  such  figure  must  certainly  exceed  100  meters.  In 
Paraguay  the  beds  are  also  more  arenaceous.  On  the  other  hand, 
the  group  becomes  more  calcareous  to  the  northeast,  and  in  the 
neighborhood  of  Rio  Claro  in  Sao  Paulo,  white  and  gray  fine-grained 
crystalline  limestones  play  an  important  part,  being  actually  quarried 
as  a  source  of  lime. 

The  group  is  traceable  from  Palmeira  in  that  quarter  southwest- 
ward,  making  a  sweeping  curve  through  Parana  that  passes  60  km. 
to  the  west  of  Tibagy  and  then  turns  east  of  south  through  Iraty  to 
Lauro  Muller  and  thence  to  the  Atlantic  coast.  Possibly  overlapped 
just  a  little  to  the  northeast  of  Porto  Alegre  by  higher  divisions,  the 
Iraty  has  been  proved  by  occasional  outcrops  and  by  borings  along 
the  southern  side  of  the  Jacuhy  River,  running  nearly  due  westward, 
passing  to  the  north  of  Sao  Sepe  and  thence  through  Sao  Gabriel, 
after  which  its  exact  course  is  not  known  with  certainty,  but  it  is 
exposed  on  the  Uruguayan  border  between  Paso  Maria  Isabel  and 
Paso  Minarano,  and  turning  southwestward  stretches  along  the  base 

72  White  (1908),  pp.  181-191;  Oliveira  (1918),  p.  16. 


GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY 


79 


of  the  Cerro  Largo  and,  curving  through  Fraile  Muerto,  strikes  west- 
northwestward  toward  the  Rio  Negro.  It  was  cut  in  the  boring  at 
Tacuarembo  beneath  the  Triassics  and  is  known  to  reappear  on  the 
farther  side  of  the  basin  at  Villarrica  in  Paraguay,  where  fossil  bones 
occur,  while  Millward  has  reported  the  extension  of  this  and  the 
Estrada  Nova  in  the  south  of  Matto  Grosso  and  Goyaz,  apparently 
from  the  foot  of  the  Sierra  de  Aquidauana  northeastward  past  Rio 
Bonito  to  Rio  Verde,  but  this  quarter  is  as  yet  only  slightly  known. 

Fossils — Important  is  the  frequency  with  which  the  singular 
little  reptile  Mesosaurus  has  been  found  at  various  points  along  the 
known  huge  extent  of  outcrop  within  certain  layers  in  the  black 
shales.  In  places  the  shales  are  just  crowded  with  skeletons  and  in¬ 
deed,  not  infrequently,  such  remains  are  discovered  in  bore-hole 
cores.  Along  with  it  occurs  the  very  closely  allied  but  generally 
larger  form  Stereo  sternum,  though  curiously  it  is  stated  that  the  latter 
is  practically  confined  to  the  limestone  layers.  Some  splendid  show 
specimens  of  both  these  reptiles,  and  of  Stereosternum  embedded  in 
white  limestone,  are  displayed  in  the  State  Museum  at  Sao  Paulo. 

It  is  essential  to  observe  that  long  ago  Lydekker,  and  recently 
that  high  authority  Von  Huene,73  have  refused  to  recognize  the  gen¬ 
eric  status  of  Stereo  sternum,  both  regarding  it  as  a  species  of  Meso¬ 
saurus,  and  for  the  present  we  shall  therefore  consider  them  as 
Mesosaurus  tumidus  and  M.  brasiliensis  respectively.  Von  Huene, 
reviewing  the  known  South  African  species,  has  furthermore  placed 
them  all  in  the  one  form,  M.  tenuidens,  with  the  opinion  that  the 
latter  is  probably  distinct  from  the  two  species  represented  in  Brazil. 
Noteworthy  is  the  fact  that  this  unique  creature — clearly  a  free- 
swimming  reptile — has  as  yet  been  found  only  in  the  Parana  basin 
and  not  elsewhere  in  South  America,  although  strata  of  equivalent 
age  are  certainly  represented  elsewhere  in  that  continent,  while 
across  the  Atlantic  it  has  been  recorded  at  intervals  from  the 
Kaokoveld  in  Southwest  Africa  down  to  the  south  of  the  Karroo, 
though  not  to  the  east  or  northeast  (see  Fig.  7,  on  which  the  approx¬ 
imate  limits  are  indicated). 

Walther  has  mentioned  the  finding  on  the  Rio  Jaguar ao  in  north¬ 
eastern  Uruguay  of  impressions  resembling  those  described  by  White 
from  the  Bonito  of  Santa  Catherina  under  the  name  of  Hastimima, 
originally  thought  to  be  a  plant,  but  later  discovered  to  belong  to  an 
eurypterid.  Doctor  Pacheco  has  informed  me  of  the  occurrence  in 
Sao  Paulo  State  of  Schizodus  (?),  while  Broili  in  a  letter  to  Walther 
has  identified  certain  fish-scales  from  the  boring  at  Isla  de  Zapata  near 
Melo  as  belonging  to  a  ganoid.  Not  improbably  the  fossil  wood 
Dadoxylon  pedroi  Zeill.  comes  from  the  Iraty  of  Sao  Paulo.  Derby  has 
furthermore  remarked  upon  the  association  in  Sao  Paulo  State — an 

73  Von  Huene  (1925),  pp.  118-120. 


80  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 


important  one — of  Psaronius  with  Stereosternum  and  Lycopodiopsis 
derbyi ,  and  the  latter  has  been  discovered  even  above  the  Iraty 
group.74 

Just  as  in  the  Cape  Province  with  the  shales  of  the  White  band, 
so  the  bituminous  nature  of  the  Iraty  shales  has  led  to  much  pros¬ 
pecting  for  coal,  while  their  petroliferous  odor  when  broken  has 
incidentally  been  responsible  for  the  drilling  of  several  deep  bore¬ 
holes  in  search  of  oil;  in  both  countries,  it  might  be  remarked,  the 
shales  are  often  sapropelitic  in  character  and  will  furnish  oil  on 
distillation. 

The  exclusive  presence  of  Mesosaurus  and  the  outstanding  litho¬ 
logical  similarities,  down  to  minutiae,  render  the  correlation  of  the 
Iraty  group  with  the  White  band  of  the  Dwyka  series  absolutely  assured , 
although  a  distance  of  6,300  km.  separates  their  nearest  outcrops, 
whereas  these  two  zones  are  traceable  not  more  than  1,000  km. 
away  from  the  Atlantic  shore  in  either  case. 

(8)  The  Estrada  Nova  Group 

The  Estrada  Nova  group,  or,  as  it  has  been  called  in  Sao  Paulo, 
the  Corumbatahy  group,  follows  the  Iraty  with  seeming  conformity 
from  just  south  of  Palmeira  in  that  State  to  Tacuarembo  in  Uruguay, 
an  assemblage  that  seldom  has  good  exposures,  crumbling  readily 
and  so  releasing  the  cherty  concretions  that  form  so  characteristic 
a  feature  of  it.75 

The  beds  are  arenaceous  shales — gray,  dark  greenish  or  reddish, 
pink,  lavender  or  lilac — always  well-laminated,  with  intercalated 
bands  of  relatively  pure  sandstone  very  rich  in  siliceous  nodules,  and 
nodules  of  chert,  together  with  some  white  limestone.  While  most 
of  the  bright  coloration  is  certainly  due  to  weathering,  some  of  it  is 
original,  as  borings  have  proved,  and  the  superficial  pink,  heliotrope, 
or  lilac  tints  help  materially  to  distinguish  this  group  from  the  lower 
division,  although  proving  a  source  of  trouble  when  attempting  to 
discriminate  it  from  the  succeeding  deeply  colored  strata.  Taken 
by  I.  C.  White  as  the  top  of  this  group,  because  it  was  overlain  by  the 
Triassic  Rio  do  Rasto  series,  is  the  Rocinha  limestone,  a  band  attain¬ 
ing  the  maximum  thickness  of  3  meters,  though  only  rarely  exposed, 
and  known  along  the  Rio  Rocinha  in  Santa  Catherina,  at  Therezina 
in  Parana,  and  Fartura  in  Sao  Paulo,  but  which  is  supposed  to  be 
represented  at  other  points  by  cherty  beds  with  fossil  mollusca.76 
The  thickness  of  the  group  is  taken  as  150  meters,  but  the  inclusion 
of  certain  higher  beds  in  Parana  that  can  be  placed  in  the  Estrada 
Nova  would  bring  up  the  value  in  that  State  to  fully  300  meters. 

The  Estrada  Nova  is  important  because  of  its  fossiliferous  charac- 


74  White  (1908),  p.  371. 

75  Ibid.,  pp.  191-195. 


76 Oliveira  (1918),  p.  17. 


GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY 


81 


ter,  indicative  of  deposition  in  an  estuary  with  occasional  incursions 
of  the  ocean.  At  Rio  Claro,  east  of  Marechal  Mallet  Station  in 
Parana,  mollusca  have  been  found  in  the  cherts  and  siliceous  oolites 
(Zone  i)  and  also  at  a  slightly  higher  level  in  a  calcareous  sand¬ 
stone  (Zone  2),  these  two  fossiliferous  horizons  having  been  recog¬ 
nized  at  several  other  points  to  the  west  of  the  railway  between 
Marechal  Mallet  and  Iraty,  these  occurrences  having  been  detailed  by 
Oliveira  and  certain  of  the  forms  described  by  Holdhaus. 77  (See  below.) 

The  sequence  that  I  was  able  to  examine  between  Marechal 
Mallet  and  Rio  Claro  is  a  rather  important  one.  In  the  first  bore-hole, 
situated  4  km.  to  the  west  of  Rio  Claro,  there  are  fully  200  meters 
of  beds — bluish-green  shales  with  white  calcareous  and  sandy  well- 
banded  layers — overlying  the  Iraty  group.  The  soft  fossiliferous 
sandstone  with  “Solenomorpha  ”  etc.,  taken  by  Oliveira  as  the  top  of 
the  Estrada  Nova,  crops  out  about  40  meters  higher  still,  yet  above 
the  latter  the  rising  ground  on  the  road  to  Marechal  Mallet  displays 
for  a  vertical  distance  of  40  meters  similar  strata,  except  for  the 
absence  of  cherts.  Above  this  the  beds  become  more  arenaceous,  yet 
not  until  nearly  75  meters  above  the  “ Solenomorpha ”  band  do  strata 
make  their  appearance,  having  strong  red  coloration,  from  which 
point  red  and  purple  sandstones  and  mudstones  are  visible,  followed 
by  buff  fine-grained  sandstones  and  greenish  mudstones  and  shales, 
with  intrusions  of  dolerite  up  to  the  summit  of  the  Serra  do  Tigre. 

The  upper  portion  of  these  300  meters  of  beds  overlying  the  Iraty 
could  preferably  be  included  in  the  Estrada  Nova,  despite  the 
absence  of  cherts,  the  higher  strata  with  bright-colored  shales  and 
mudstones  being  allotted  to  the  Rio  de  Rasto. 

In  Rio  Grande  do  Sul  this  group  has  nowhere  been  mapped,  but 
in  Uruguay,  entering  from  Brazil,  it  is  known  to  run  southward 
down  the  Canada  de  Ibanez  past  Melo  and  a  little  to  the  north  of 
Fraile  Muerto  and  thence  northwestward  across  the  Rio  Negro  and 
up  the  Tacuarembo  Valley,  covering  a  wide  area  to  the  south  and 
east  of  the  town  of  that  name.  It  is  also  known  to  surround  much  of 
the  granite  inlier  of  the  Department  of  Riviera. 

The  only  place  where  I  was  able  to  study  these  beds  in  Uruguay 
was  in  the  shallow  basin  crossed  by  the  railway  between  Fraile 
Muerto  and  Melo,  where,  proceeding  from  the  former  station,  the 
laminated  olive  and  buff  clayey  shales  with  ribs  of  sandstone  and 
limestone  belonging  to  the  Iraty  pass  up  at  kilometer  390  into 
greenish,  lavender,  and  then  into  red,  carmine,  and  white  laminated 
beds,  with  thin  layers  of  white  cherty  rock,  and  are  hence  very  like 
the  Corumbatahy  group  of  Sao  Paulo.  Between  kilometers  392  and 
393  some  red  sandstones  appear,  and,  though  the  well-laminated 
character  of  the  shales  persists  for  a  short  distance,  the  beds  give  way 

77 Holdhaus  (1919). 


82  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

to  a  group  of  less  well  bedded  red  and  variegated  clays  and  mud¬ 
stones  and  red  sandstones  somewhat  evenly  stratified,  sometimes 
cross-bedded,  as  at  395.  At  kilometer  400,  just  before  reaching 
Banado  de  Medina,  a  thick  sandstone  of  this  kind  rests  on  red  clays, 
and  such  arenaceous  beds  extend  almost  to  Melo  and  occupy  a  con¬ 
siderable  area  to  the  north  and  northwest.  All  the  rocks  from  about 
kilometer  394  onward  can,  I  think,  be  taken  as  representing  the  Rio 
do  Rasto  group.  The  bore-hole  at  Buena  Vista,  20  km.  north  of 
Melo,  reveals  a  similar  sequence  with  about  245  meters  of  strata 
ascribable  to  the  Estrada  Nova,  while  Walther  states  that  to  the 
south  of  Melo  siliceous  concretions  have  weathered  out  from  these 
beds  in  great  numbers. 

In  Paraguay,  according  to  Beder,78  there  are  at  Villarrica,  in  addi¬ 
tion  to  the  undoubted  Iraty  cherts,  some  with  oolitic  structure  and 
also  some  higher  reddish  friable  sandstones  that  have  yielded  species 
of  “ Solenomorpha .”  According  to  Leme,79  Millward  has  found  in  the 
south  of  Goyaz  similar  beds  with  plant  fossils  and  lamellibranchs, 
presumably  belonging  to  this  group  and  covering  a  wide  area  round 
about  Rio  Bonito  and  Jatahy  and  thence  southwestward  towards 
Aquidauana  on  the  railway  to  Porto  Esperanga. 

(9)  The  Fossils  of  the  Estrada  Nova 

The  stratigraphical  position  of  the  Estrada  Nova  is  at  the 
moment  involved,  as  this  so-called  “group”  would  appear  to  include 
beds  of  rather  different  ages.  Of  the  lamellibranchs  that  occur  at 
a  number  of  points  in  Parana,  Holdhaus80  has  described  several 
species  of  Solenomorpha  and  one  of  Sanguinolites ,  maintaining  a 
Permian  age  for  the  formation.  Dr.  Reed,  who  has  determined  the 
mollusca  collected  by  me  from  Zones  1  and  2  at  Rio  Claro,  doubts 
Holdhaus ’s  identifications,  having  discovered  in  these  two  horizons 
only  Trias  sic  forms,  such  as  Pachycardia,  Anodontophora ,  Myophoria , 
and  Schafhautlia,  as  detailed  on  page  150. 

Although  the  sequence  has  hitherto  been  regarded  as  an 
unbroken  one,  a  stratigraphical  hiatus  must  he  present ,  though  the 
precise  plane  thereof  has  not  yet  been  located  in  the  field.  Any 
beds  below  this  surface  of  discontinuity  must  lie  conformably  upon 
the  Iraty  and  hence  belong  to  the  Permian ;  those  above  it  being  of 
Triassic  age,  must  perforce  be  associated  with  the  overlying  Rio 
do  Rasto  and  are  presumably  conformable  therewith.  Future 
work  will  no  doubt  bring  about  a  better  re-arrangement  of  the 
Estrada  Nova. 

Fish  scales  and  bones  have  been  discovered,  also  silicified  wood  has 
been  determined  by  D.  White  as  Dadoxylon  nummularium,  a  species 
in  which  no  annual  rings  can  be  made  out,  though  Walther  has  found 

78Beder  (1923),  p.  11.  79  Leme  (1924),  p.  179.  80 Holdhaus  (1919). 


GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY  83 

other  kinds  in  Uruguay  in  which  the  rings  are  perfectly  well  defined. 
At  kilometer  post  124  on  the  railway,  17  km.  south  of  Iraty,  I 
obtained  a  fragment  of  Glossopteris ,  while,  from  near  the  top  of  the 
group  in  the  area  between  Marechal  Mallet  and  Roxo  Roiz,  Zeiller 81 
has  determined  Glossopteris  browniana ,  G.  angustifolia,  Txniopteris 
possibly  T.feddeni,  Pecopteris  sp.,  Cladophlebis  sp.,  and  equisetaceous 
stems.  A  frond  in  the  Geological  Survey  Museum,  Rio,  labeled 
“Glossopteris”  belongs  probably  to  the  Triassic  genus  Sagenopteris. 

(10)  The  Triassic  Overlap 

Before  proceeding  to  the  description  of  the  higher  groups,  it  will 
be  proper  to  discuss  this  particular  question  because  of  the  light 
which  it  sheds  on  the  succession,  more  particularly  in  Parana. 

Evidence,  palaeontological  as  well  as  stratigraphical,  has  gradu¬ 
ally  been  accumulating,  as  can  be  found  on  perusing  the  writings  of 
Walther,  Baker,  and  others,  to  show  that  a  break  must  exist  within 
the  Parana  basin  between  beds  that  are  certainly  Triassic  and  those 
that  are  definitely  Permian  or  older,  thus  tending  to  bring  the  strati¬ 
graphy  of  this  part  of  the  continent  into  harmony  with  that  of  western 
Argentina.  Future  work  will  have  to  be  directed  toward  the  mapping 
of  the  “  disconformity ,  ”  but  the  gap,  so  far  as  can  be  made  out, 
seemingly  represents  the  whole  of  the  uppermost  Permian  and  perhaps 
much  of  the  lower  Triassic. 

In  the  north  of  Sao  Paulo  the  Triassic  Botucatu  sandstone  reposes 
on  the  ancient  floor  of  schists  near  the  Agua  Suja  diamond  mine  and 
at  Franca,  while  farther  south,  at  Monte  Santo  the  Pyramboia — the 
equivalent  of  the  Rio  do  Rasto — rests  directly  upon  the  Itarare 
tillite.  West  of  Mococa,  on  the  border  of  Minas  Geraes,  Doctor 
Pacheco  informs  me  that  the  lower  groups  have  suffered  some  flexing, 
which  action  may  have  been  due  to  inter-Triassic  earth-movements. 
At  Palmeira  the  Pyramboia  rests  on  the  Iraty,  and  farther  south  on 
the  Corumbatahy  or  Estrada  Nova,  which  relationship,  so  far  as 
can  be  gathered,  thenceforward  holds  good  into  Santa  Catherina, 
though  the  latest  geological  map  of  Parana  (1925 ;  scale  1 : 1,000,000) 
by  Doctor  Oliveira  makes  the  Rio  do  Rasto  transgress  across  the 
Itarare  and  Passa  Dois  in  the  vicinity  of  Thomazina.  In  Santa 
Catherina,  I.  C.  White  observed  the  contact  with  the  Rocinha  lime¬ 
stone  to  be  an  unconformity  over  the  short  length  exposed. 

The  Rio  do  Rasto  extends  on  the  coast  from  Morro  Conventos 
(lat.  2  90)  to  Conceiao  do  Arroio  and  thence  westward  to  the  north  of 
Porto  Alegre,  but  according  to  information  from  Doctors  Rego  and 
Lofgren  this  formation  also  builds  the  large  hill  to  the  east  of  that 
town  and  stretches  past  Vumiao  into  the  Serra  Geral  ( not  the  great 
range  of  that  name  in  Santa  Catherina),  immediately  to  the  east. 

81Holdhaus  (1919),  p.  30. 


84  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

It  is  not  improbable,  judging  from  the  height  to  which  the  granite 
rises  at  Porto  Alegre,  that  the  Rio  do  Rasto  overlaps  across  the 
Bonito  group  of  the  Gravatahy  coal-field  to  come  to  rest  on  the  gran¬ 
ite  in  the  south.  Proceeding  up  the  Jacuhy  Valley,  with  its  exten¬ 
sive  alluvial  plains,  shales  regarded  as  Iraty  were  observed  by  Doctor 
Rego,  3  km.  west  of  Rio  Pardo,  the  beds  round  about  belonging  to 
the  Rio  do  Rasto.  The  deep  boring  at  Ferreira,  however,  close  to 
Cachoeira,  which  I  saw  in  progress,  proved  the  Rio  do  Rasto,  down 
to  73  meters  at  least,  with  the  Estrada  Nova  (including  a  30-meter 
sheet  of  dolerite)  beneath  and  the  top  of  the  Iraty  at  260  meters. 

While  the  Tuber  ao  and  Iraty  make  a  sweeping  curve  around  the 
granite  axis  in  the  country  between  Sao  Sepe  and  Bage,  followed 
farther  to  the  north  by  the  Rio  do  Rasto  in  regular  fashion,  Wal- 
ther’s 82  observation  of  an  area  at  Cagapava  made  by  the  Triassic 
resting  directly  on  the  crystallines  is  of  great  importance.  Between 
Cagapava  and  the  Seibal  Copper  Mine  the  sediments  are  only  from 
6  to  8  meters  thick,  with  a  red  basal  conglomerate,  and  are  covered 
by  highly  vesicular  amygdaloids,  presumably  the  equivalents  of  the 
Serra  Geral  eruptives.  At  Sao  Sebastiao,  on  the  railway  to  Bage, 
another  outlier  occurs. 

Over  much  of  Uruguay,  just  as  in  Brazil,  the  Rio  do  Rasto  has 
not  yet  been  carefully  delimited  from  the  top  of  the  rather  lithologic¬ 
ally  similar  Estrada  Nova,  and  a  pseudo-conformity  probably  exists, 
as,  for  example,  in  the  Department  of  Cerro  Largo,  the  younger  group 
being  distinguishable  by  the  predominance  of  red  sandstones,  often 
massive  and  cross-bedded.  But  in  the  important  section  described 
by  Walther 83  in  the  Cerro  Mirinaque  east  of  Tacuarembo,  80  meters 
of  these  arenaceous  red  beds  rest  directly  on  the  granite,  whereas  at 
Tacuarembo,  where  such  strata  compose  both  the  plain  and  the 
neighboring  spurs,  the  rocks  cut  in  the  deep  boring  embrace  the 
whole  of  the  Iraty  and  Tuber  ao.  Examination  of  the  core  leads  me 
to  believe  that  the  bright  cream,  red,  and  brown  sandstones,  gritty 
at  their  base,  are  here  126  meters  thick  and  rest  upon  24  meters  only 
of  maroon  and  heliotrope  mudstones  that  can  be  ascribed  to  the 
Estrada  Nova  and  these  in  turn  upon  the  Iraty,  etc.  The  overlap  is 
also  discovered  far  to  the  south,  nearly  100  km.  away  from  the  main 
basin,  where,  on  the  Barrija  Negro  in  the  Minas  district,  Walther84 
has  recorded,  resting  upon  the  crystal  lines,  gray,  yellow,  and  dark- 
red  ripple-marked  sandstones,  coarse  conglomerates,  etc.,  overlain 
by  vesicular  basalt.  Boring  No.  51  in  the  soil-covered  region  at 
Santa  Rosa  on  the  Melo  Railway,  55  km.  from  Montevideo,  proved 
red  and  chocolate-colored  amygdaloid  down  to  78  meters  at  least, 
and,  after  piercing  some  softer  rock  beneath,  penetrated  a  red  con- 


82  Walther  (1912)  and  (1912a). 

83  Ibid.  (1919),  p.  1 12. 


84 Ibid.  (1912),  p.  401. 


GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY  85 

glomerate  with  boulders  of  gneiss,  grits,  quartzites,  etc.,  down  to  in 
meters.  The  red  gritty  sandstones  at  Sauce,  however,  appear  to  me 
to  be  probably  of  Cretaceous  or  Tertiary  age. 

From  the  record  of  the  San  Cristobal  bore-hole85  in  Santa  Fe, 
Argentina,  the  Rio  do  Rasto  apparently  rests  on  the  Bonito  at  about 
1,140  meters,  the  Iraty  not  being  identifiable,  while  that  at  Galeguay 
in  Entre  Rios  east  of  Rosario  shows  beneath  463  meters  of  Neogene 
36  meters  of  volcanics  (fine-grained  porphyrites)  resting  directly 
upon  amphibolite  without  any  Botucatu.  According  to  Leme,  the 
transgression  is  again  to  be  found  far  to  the  northwest,  where,  on  the 
west  side  of  the  basin  at  Aquidauana,  the  Botucatu  followed  by  vol¬ 
canics  reposes  upon  schists. 

These  various  and  isolated  observations,  though  scattered  over 
an  enormous  area,  collectively  justify  our  concluding  that  the  Rio  do 
Rasto  must  in  a  number  of  places,  chiefly  be  it  noted  on  the  margins 
of  the  basin,  overlap  and  be  unconformable  to  the  lower  groups,  thus 
forming  a  parallel  to  the  Karroo  system.  Within  the  basin,  however, 
the  molluscan  horizons  (Triassic)  would  prove  that  this  plane  of 
overlapping  is  there  situated  somewhere  within  the  limits  of  the 
Estrada  Nova  as  correctly  defined,  presumably  nearer  its  base, 
these  marine  beds  being  elsewhere  overstepped  by  the  continental 
Rio  do  Rasto.  The  tracing  out  of  this  break  will  be  an  important 
investigation  for  the  future.  The  circumstances  in  the  Parana  basin 
would  seem  to  form  an  almost  exact  parallel  to  those  in  the  north  of 
the  Orange  Free  State  in  South  Africa,  where,  by  the  dying  out  of 
the  Molteno  beds,  two  maroon  and  mainly  argillaceous  formations 
are  brought  together,  the  upper  Triassic  Red  beds  coming  to  rest 
directly  upon  the  lower  Triassic  upper  Beaufort  beds  in  that  area, 
but  in  the  central  Transvaal  upon  the  lower  Permian  Ecca  beds 
generally. 

Attention  can  also  be  drawn  to  the  transgression  of  the  Trias- 
Rhastic  (Stage  IV)  in  Argentina  across  Stages  III,  II,  and  even  I  of 
the  Paganzo,  as  detailed  earlier,86  of  which  Stage  II  displays  many 
points  of  lithological  similarity  with  the  Passa  Dois  series.  In  the 
Parana  basin,  however,  unlike  the  pre-Cordilleran  region,  the  older 
groups  were  only  slightly  warped  and  eroded  during  the  early 
Triassic. 

(11)  The  Sao  Bento  Series — Triassic 

In  the  Parana  basin  this  is  divided  into : 

3.  Serra  Geral  eruptives,  up  to  500  meters  in  thickness 

2.  Botucatu  sandstone _ o  to  100  meters  in  thickness 

1.  Rio  do  Rasto  beds  ...  100  to  400  meters  in  thickness  usually 

This  arrangement,  it  will  be  observed,  differs  slightly  from  the 
scheme  proposed  by  I.  C.  White. 

85  Hausen  (1919),  p.  35. 


86  Section  F  (5) . 


86  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

The  placing  of  the  lowest  of  these  devisions  in  the  Permian,  as  has 
been  done  by  Oliveira,87  has  nothing  to  support  it,  since  the  mollus- 
can  remains  found  beneath  it  belong  to  undoubtedly  Triassic  forms. 

The  beds  again  with  vertebrate  fossils  while  overlapping  the 
older  groups  in  certain  places,  pass  without  a  break  into  the  Botu¬ 
catu,  where  that  division  is  recognizable,  overlain  in  turn  by  and 
intimately  associated  with  the  basic  lavas  or  “traps.  ” 

The  Triassic  occupies  a  huge  region — the  greater  part  of  the 
basin  in  fact — for  which  the  volcanic  group  is  mainly  responsible 
areally.  In  places  it  is  unconformably  covered  by  patches  of  the 
Bauru  (Cretaceous)  beds,  while  to  the  west  the  succession  passes 
beneath  the  Neogene  of  the  lower  Parana  River,  though  whether 
some  faulting  has  been  responsible  for  its  lower  position  in  that  direc¬ 
tion  is  not  yet  assured. 

(12)  The  Triassic  Continental  Sediments 

The  Rio  do  Rasto ,88  also  called  the  Pyramboia  group  in  Sao 
Paulo,  is  so  closely  associated  with  the  Botucatu  (or  Sao  Bento) 
sandstone,  that  the  two  groups  must  be  described  together.  Appar¬ 
ently  only  in  the  south  of  Parana  and  in  Santa  Catherina,  according 
to  the  account  of  White,  is  the  upper  division  well  differentiated  and 
clearly  distinguishable  from  the  lowrer ;  in  Rio  Grande  do  Sul  it  is  in 
places  not  clearly  separable,  while  over  much  of  Uruguay  the  paler 
color  of  the  top  of  the  sedimentary  formation  is  largely  a  secondary 
character.  The  term  Botucatu,  furthermore,  seems  to  have  been  also 
used  by  the  Geological  Survey  of  Brazil  for  the  sedimentary  inter¬ 
calations  between  the  lavas. 

The  friability  of  the  lower  red  sandstones  and  mudstones, 
coupled  with  the  hardness  of  the  overlying  Botucatu  or  the  traps, 
has  been  responsible  for  an  escarpment  traceable  nearly  right  around 
the  basin,  this  feature  being  bordered  by  many  picturesque  outliers, 
from  table-topped  to  conical.  To  a  wonderful  degree  the  rocks  and 
scenery  recall  the  “Basalt-Cave  sandstone — Red  beds”  topography 
around  Basutoland  or  in  the  Kaokoveld  and  parts  of  southern  Rho¬ 
desia.  The  development  in  Santa  Catherina  is  from  all  accounts 
most  like  that  of  Basutoland  and  the  features  seen  elsewhere  like 
those  in  Rhodesia. 

The  Rio  do  Rasto  or  Pyramboia  consists  of  friable  red,  often 
vivid,  sandstones  with  occasional  white  blotches  often  false-bedded 
on  a  large  scale;  layers  of  fine-grained  pink,  red,  purplish,  and  occa¬ 
sionally  greenish  clays  are  also  present,  but  there  is  not  the  well- 
marked  lamination  and  alteration  of  shales  and  thin  sandstones 
characteristic  of  the  Estrada  Nova,  while  the  diagonal  bedding  in 
the  sandstones  is  also  most  conspicuous. 


87 Oliveira  (1918),  p.  11. 


88  White  (1908),  pp.  197-21 1. 


GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY  87 

At  Taquara,  north  of  Porto  Alegre,  where  the  upper  part  of  the 
brown -red  sandstones  was  of  uniform  character  through  a  thickness 
of  fully  75  meters,  I  found  the  false-bedding  most  pronounced,  the 
planes  often  dipping  at  angles  up  to  40 °  from  the  horizontal  in 
opposite  directions  in  surprising  fashion  through  individual  thick¬ 
nesses  in  some  places  of  1 2  meters  or  more  of  rock.  The  sandstone  is 
quarried  for  paving  slabs  (Plate  XII,  B ),  being  built  up  of  alternate 
laminae  of  fine-grained  rather  clayey  material  and  coarser,  friable 
“millet  seed”  grains  in  strictly  parallel  fashion  and  not  in  lenses; 
mica  is  practically  absent,  but  iron  ores  are  abundant  and  a  cal¬ 
careous  matrix  is  indicated.  In  the  coarser  bands  not  only  the  grains 
of  quartz,  but  even  those  of  feldspar  (which  are  quite  fresh),  are 
well  rounded,  and  up  to  a  millimeter  in  diameter,  and  there  can  be 
no  doubt  that  this  formation  is  of  eolian  origin.  The  same  was  found 
to  be  the  case  about  Sant’  Anna  and  Riviera,  on  the  border  of  Uru¬ 
guay,  the  smaller  grains  tending  to  be  subrounded.  Doctor  Pacheco 
informs  me  that  the  sand  grains  in  the  Pyramboia  of  Sao  Paulo  are 
well  rounded,  each  coated  with  a  thin  pellicle  of  iron  oxide. 

In  the  basal  part  of  the  group,  as  seen  along  the  railway  between 
Porto  Alegre  and  Santa  Maria  and  again  between  Rivera  and  Tacua- 
rembo  in  Uruguay  the  sandstones  become  fine-grained  and  pass 
into  mudstones  of  uniform  nature  and  wonderfully  brilliant  hue 
wherever  freshly  exposed,  while  irregular  calcareous  patches  are 
common.  Crumbling  readily,  they  give  rise  to  sandy  or  loamy  soils 
of  wide  distribution,  from  which  the  red  tint  has  been  removed  by 
bleaching.  What  were  considered  to  be  the  basal  beds  were  cut  in 
the  Tacuarembo  boring  at  126  meters  and  were  coarser  and  gritty. 
Some  curious  veins  or  reefs,  within  which  the  sandstones  have  been 
partially  or  wholly  silicified,  are  frequent  in  northern  Uruguay,  as 
described  by  Walther;  from  examination  of  two  of  these  near  Paso 
del  Cerro  it  seems  not  improbable  that  they  have  been  produced  by 
heated  waters  descending  through  fissures  from  the  lavas  above. 

In  the  northeastern  part  of  Paraguay  the  red  sandstones  inter- 
bedded  with  and  capped  by  basalts  occur  at  Bella  Vista  and  build 
the  Sierra  de  Amambay,  while  they  extend  northeastward  from 
Aquidauana  into  Goyaz  and  onward,  with  a  large  outlying  area  to  the 
northwest  in  the  Chapada. 

The  thickness  of  the  group  must  be  considerable;  at  least  400 
meters  between  Taquara  and  Santa  Maria,  but  less  than  half  that  in 
Parana,  Santa  Catherina,  and  Uruguay,  and  according  to  Baker89 
under  100  meters  in  the  north.  In  the  San  Cristobal  bore-hole  it  is 
perhaps  240  meters  thick. 

The  Botucatu  sandstone  is  a  little  coarser  and  paler,  generally 
creamy  or  gray,  though  sometimes  terra-cotta  or  red,  and  then  hard 

89  Baker  (1923),  p.  68. 


88  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

to  distinguish  from  the  underlying  Rio  do  Rasto,  particularly  as  it 
tends  to  display  the  same  conspicuous  false-bedding.  Pacheco  states 
that  in  Sao  Paulo  the  grains  are  usually  angular,  but  at  Ityrapina 
I  found  the  sandstones,  with  which  basalt  flows  are  interbedded,  to 
be  pinkish,  gritty  though  friable,  with  quartz  grains  up  to  3  mm.  in 
diameter,  many  of  them  oval  or  spherical,  while  the  bulk  were  sub- 
angular  and  not  angular.  Here  the  group  was  over  200  meters  thick. 

In  Parana  and  Santa  Catherina  the  sandstone,  according  to 
White,90  is  very  massive  and  makes  long  lines  of  yellow  cliffs  sinking 
in  a  southerly  direction  until  they  come  down  almost  to  sea-level 
behind  Torres.  The  deep  bore-hole  No.  3,  situated  20  km.  inland 
from  that  place,  proved,  according  to  Doctor  Lofgren,  122  meters  of 
Botucatu  overlying  145  meters  of  Rio  do  Rasto  at  least,  but,  curi¬ 
ously  to  the  southwest,  neither  at  Taquara  nor  at  Santa  Maria,  is 
the  upper  member  represented,  though  it  is  reported  that  a  pale 
sandstone  underlies  the  lavas  in  the  ragged  escarpment  between 
these  two  towns. 

Traced  from  Rivera  to  Tacuarembo,  the  top  of  the  Rio  do  Rasto 
immediately  underlying  the  basalts  develops  a  harder  facies,  paler 
in  exposures,  and  thus  resembles  the  Botucatu  superficially,  but  is 
actually  red  when  fractured,  and  moreover  shows  the  same  degree  of 
false-bedding  as  in  the  Rio  do  Rasto  below.  This  feature  can  be 
.ascribed  mainly  to  the  indurating  action  of  the  basalts,  for  the  top  is 
often  brecciated.  This  material  commonly  makes  scarps  and  some¬ 
times  caps  isolated  hills,  as  in  the  symmetrical  Tres  Cerros  east  of 
Tacuarembo  or  in  the  similarly  styled  elevations  to  the  north  of 
Uruguay  ana  in  Argentina  mentioned  by  Hausen.91 

Whether  the  Botucatu  is  merely  a  slightly  different  facies  of  the 
uppermost  part  of  the  Rio  do  Rasto,  or  whether  it  is  really  a  separate 
formation  only  partially  developed  or  missing  in  certain  portions  of 
the  basin,  thus  allowing  the  basalts  to  repose  directly  upon  the  lower 
division,  is  not  quite  clear,  and  only  detailed  mapping  could  settle 
this  point,  which  is  of  no  great  importance,  fortunately. 

There  can  hardly  be  any  doubt,  however,  as  to  the  predomi¬ 
nantly  eolian  origin  of  the  Sao  Bento  sediments,  which  is  all  the  more 
compelling  when  comparison  is  made  with  the  obviously  equivalent 
Cave  and  Forest  sandstone  (Stormberg)  of  the  Cape  and  Southern 
Rhodesia,  with  their  underlying  red  beds.  The  first  named  is  similar 
lithologically  to  the  Botucatu,  displaying  features  indicative  of  a 
loess-like  origin,  while  the  second,  as  shown  by  “millet-seed”  grains 
and  strong  false-bedding,  is  of  eolian  origin,  the  sediments  in  both 
cases  being  followed  by  effusion  of  basalts  in  which  certain  inter¬ 
bedded  sandstones  occur. 


90  White  (1908),  pp.  2 1 1-2 1 7. 


91  Hausen  (1919),  PI.  VI. 


GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY 


89 


(a)  Fossils — Under  such  circumstances  the  life  of  the  period 
would  have  been  scanty  and  the  poverty  of  fossils  would  thus  find 
an  explanation.  Silicified  wood  is  abundant  at  many  points  in  the 
Rio  do  Rasto,  both  low  down  as  well  as  at  the  top,  for  example  at 
Rivera;  such  is  probably  mainly  referable  to  Dadoxylon. 

Of  Filicales  we  have  only  the  record  of  Cladophlebis ,  determined 
by  Kurtz92  as  C.  denticulcita  Brongt.  from  the  base  of  the  Tres  Cerros 
near  Tacuarembo,  but  which  after  an  examination  I  feel  sure  is  a 
distinct  and  probably  new  species,  though  closely  related  to  the 
foregoing,  which  is  a  Rhaetic-Liassic  form. 

From  a  point  a  little  to  the  south  of  Santa  Maria  da  Bocca  do 
Monte  the  remains  were  obtained  of  Scaphonyx  fischeri  S.  Woodw.,93 
a  dinosaur  allied  to  Euskelesaurus  from  the  upper  Triassic  Red  beds  of 
South  Africa,  below  which  latter  horizon  dinosaurs  have  not  yet  been 
discovered.  Leme94  mentions  the  finding  of  a  dinosaur  allied  to 
Scaphonyx  at  Cambembe,  50  km.  to  the  north  of  the  Chapada  in 
Matto  Grosso,  while  Von  Ihering  has  recorded  a  dinosaur  tooth  in 
the  sandstone  of  Sao  Jose  do  Rio  Preto,  450  km.  to  the  northwest  of 
Sao  Paulo.  Baker  has  noted  the  presence  of  bones  near  the  coast  to 
the  northeast  of  Torres. 

A  layer  in  the  core  from  the  bore-hole  at  Ferreira  in  Rio  Grande 
do  Sul,  cutting  the  lower  part  of  the  Rio  do  Rasto,  yielded  me  valves 
of  a  small  Estheria  almost  circular  in  outline  and  certainly  distinct 
from  the  Cyzicus  ( Estheria )  draperi  so  common  in  Argentina. 

It  is  important  to  note  that  as  yet  no  forms  ascribable  to  the 
Permian  have  been  found  in  the  sediments  of  the  Sao  Bento  series 
which  must  be  considered  as  of  Trias-Rhxtic  age. 

(13)  The  Serra  Geral  Eruptives  or  Traps  and  the  Associated  Sediments 

Crowning  the  Botucatu,  or  the  Rio  do  Rasto,  where  the  former 
can  not  definitely  be  differentiated  therefrom,  comes  a  great  capping 
of  lavas,  basaltic  to  andesitic  in  composition,  while  in  certain  locali¬ 
ties  sediment  must  have  been  in  course  of  deposition  during  inter¬ 
vals  of  quiescence  to  show  up  now  as  intercalations  between  the 
lavas,  though  only  in  the  lower  part  of  the  volcanic  group.  Elsewhere, 
as  in  western  Parana  and  Santa  Catherina  and  in  parts  of  Uruguay, 
only  volcanic  material  is  to  be  found. 

Attention  must  be  drawn  to  Woodworth’s  account95  dealing  with 
the  trap  plateaus  of  Santa  Catherina,  and  particularly  to  the  valu¬ 
able  summary  by  C.  L.  Baker  entitled  ‘  ‘  The  Lava  Fields  of  Parana.  ” 96 
As  shown  in  Baker’s  map,  the  eruptives  of  the  Parana  basin  form  a 
complete  elongated  area,  1,300  km.  long,  but  of  rather  variable 
width,  500  km.  across  at  the  broadest,  narrowing  toward  the  south- 

92  Walther  (1919),  p.  107,  footnote.  94  Leme  (1924),  p.  189. 

93  White  (1908),  pp.  217-225.  95  Woodworth  (1912),  pp.  91-99. 

96  Baker  (1923) ;  the  scale  on  the  map  is  incorrectly  given. 


90  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

west  and  occupying  a  tract  of  fully  800,000  square  kilometers  in  ex¬ 
tent,  including  certain  stretches  concealed  beneath  the  Bauru  beds. 
Excepting  on  the  west,  the  lavas  generally  terminate  in  erosional  es¬ 
carpments  ;  they  frequently  give  rise  to  terraced  features  and  are 
responsible  for  the  multitude  of  rapids  and  cataracts  on  the  rivers,  out¬ 
standing  among  which  are  the  magnificent  falls  of  the  Iguassu97  with 
a  height  of  60  meters  and  those  of  La  Guayra  on  the  upper  Parana. 

While  the  contact  between  the  volcanics  and  the  sediments 
beneath  is  as  a  rule  a  perfectly  even  surface,  attention  must  be  drawn 
to  certain  irregularities  first  studied  in  the  town  of  Taquara,  north 
of  Porto  Alegre  in  Brazil,  and  seen  again  close  to  the  railway  near 
Paso  del  Cerro  and  in  the  Cuchilla  de  Tambores  io  km.  south  of 
Tacuarembo  in  Uruguay.  These  disclosed  the  fact  that  the  basalts 
in  these  three  spots  were  resting  upon  and  filling  up  shallow  hollows 
in  an  originally  uneven  surface  of  sandstone,  which  depressions  in 
every  case  trended  a  little  south  of  west,  a  feature  worthy  of  record, 
since  in  South  Africa  several  cases  are  known  of  a  similar  kind  along 
the  Basalt-Cave  sandstone  contact;  these  apparently  represent 
primitive  drainage  lines  over  the  sandy  surface  in  existence  at  the 
commencement  of  the  period  of  volcanicity.  The  section  shown  in 
Figure  6  may  therefore  be  not  an  uncommon  one. 

Flows  earlier  than  those  usually  seen  were  found  deep  down  in 
the  Botucatu  sandstone  at  Ityrapina  in  Sao  Paulo,  where  the  deep 
boring  gave  the  following  downward  section,  starting  at  the  base  of 
the  main  traps:  sandstone,  85  meters;  basaltic  flow,  15  meters;  sand¬ 
stone,  77  meters;  basaltic  flow,  3  meters;  sandstone  becoming  redder, 
more  clayey,  and  calcareous,  and  hence  transitional  to  the  Pyramboia, 
48  meters.  In  South  Africa  such  a  similar  case  has  been  recorded 
from  the  Maclear  district  of  the  Cape  Province,  where  local  eruptions 
antedated  the  dominant  period  of  volcanicity. 

Thin  sandstone  intercalations  are  recorded  by  Baker  generally,  by 
Walther  in  Uruguay,  and  by  Sobral  and  Hausen  in  Misiones,  and  are 
almost  always  medium  to  fine  grained — sometimes  finer  and  coarser 
banded — red,  red-brown,  terra-cotta,  or  even  purplish  colored, 
poorly  or  cross  bedded  sandstones  or  not  unusually  intensely  hard, 
glassy  quartzites  breaking  with  a  conchoidal  fracture  and  so  making 
very  stony  outcrops.  While  probably  much  of  this  induration  was 
effected  by  heat  from  the  overlying  lava,  the  depth  through  which 
such  hardening  extends  rather  suggests  the  action  of  hot  solutions 
carrying  silica.  On  the  other  hand,  it  should  not  be  overlooked  that 
they  might  possibly  have  acquired  some  of  this  exceptional  character 
through  original  silicification  prior  to  the  outpouring  of  the  succeed¬ 
ing  lava-flow,  for  it  is  well  known  that  under  an  arid  climate  sands 
may  be  converted  into  “surface  quartzites”  or  “silcretes”  under 

87  See  Hausen  (1919),  PI.  IV. 


GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY 


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purely  natural  conditions,  as  in  the  Kala¬ 
hari  in  South  Africa,  and  that  the  Botu- 
catu  was  apparently  accumulated  under 
such  desert  conditions.  This  is  suggestive 
because  of  the  very  similar  silicified  char¬ 
acter  beneath  the  basalts  of  the  Triassic 
Forest  sandstone  of  Rhodesia,  also  a  for¬ 
mation  of  eolian  and  presumably  of  desert 
origin.  A  noteworthy  type  of  rock  exten¬ 
sively  used  as  ballast  on  the  railways  at 
Santa  Maria  is  a  coarse  gray  grit,  which 
from  inquiry  I  afterward  found  came  from 
B arras,  on  the  railway  close  to  Passo 
Fundo,  apparently  from  an  intercalation 
relatively  high  up  in  the  volcanics,  though 
of  this  I  can  not  be  sure.  It  is  remarkable 
in  that  the  samples  picked  up  contained 
tiny  “dreikanter.  ”  Conglomerates  have 
been  reported  to  occur  in  the  Botucatu, 
and  these  are  manifestly  worthy  of  de¬ 
tailed  study  in  view  of  the  information 
they  might  yield  regarding  the  geographi¬ 
cal  and  climatic  conditions  in  Brazil  at 
the  close  of  the  Triassic  epoch. 

Above  Taquara,  on  the  road  to  Morro 
Fortaleza,  not  far  above  the  base  of  the 
lava  group,  there  crops  out  an  agglomer¬ 
ate  bed  (Fig.  6,  j),  with  a  fine,  pinkish, 
sandy  matrix  in  which  was  set  an  abund¬ 
ance  of  subangular  to  rounded  fragments 
of  different  kinds  of  lavas,  which  bed 
passes  upward  into  red  cross-bedded 
friable  sandstone  exactly  similar  to  those 
of  the  Rfo  do  Rasto  seen  in  the  town  below, 
and  ending  in  a  sharply  defined  ‘  ‘  baked 
junction  against  the  flow  overlying;  the 
band  totals  8  meters  in  thickness.  Ten 
meters  higher  up  occur  thin  sandstone 
veins  running  vertically  down  into  cracks 
in  the  underlying  basalt  from  a  higher 
thin  intercalation  of  red  sandstone ;  clearly, 
just  as  in  South  Africa,  eolian  conditions 
seem  to  have  lingered  on  while  the  earliest 
lavas  were  being  erupted. 


92  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

Some  of  the  thin  intercalated  sandstones  and  quartzites  in  the 
basin  are  reported  to  contain  fragmental  igneous  matter,  and  indeed, 
in  the  Territory  of  Misiones  in  northeastern  Argentina,  such  layers 
may  be  tufaceous  in  their  character.97  Such  bands  have  been  passed 
through  in  certain  of  the  borings,  for  example  in  those  at  Posadas, 
Solari,  and  Mercedes  (Corrientes).  It  is  worthy  of  note  that  tufa¬ 
ceous  layers  should  also  have  been  found  at  a  lower  horizon  (in  the 
Rio  do  Rasto)  in  the  bore-hole  at  San  Cristobal  (Santa  Fe)  still 
farther  to  the  west,  where  the  volcanics  were  struck  beneath  the 
Neogene  at  73  5  meters,  the  Triassic  sediments  being  cut  at  900  meters, 
underlain  by  possibly  Bonito  beds  from  about  1,141  to  1,384  meters. 
A  rather  similar  succession  was  intersected  between  860  and  1600 
meters  in  the  boring  at  Tostado,  a  little  to  the  northeast,  which  helps 
to  link  up  the  strata  of  the  Parana  basin  with  the  Paganzo  of  the 
Cordoba  and  La  Rioja  districts.  In  Laguna  Paiva  No.  2,  a  little  to 
the  north  of  Santa  Fe,  the  amygdaloids  were  struck  at  602  meters 
and  not  bottomed  at  638  meters. 

(14)  The  Volcanics 

As  various  observers  have  pointed  out,  many  of  the  flows  are 
relatively  coarse-grained,  compact  rocks  difficult  to  distinguish  from 
intrusive  sheets,  but  as  a  rule  such  types,  when  satisfactorily  exposed, 
display  vesicular  structure  at  the  top,  if  not  at  the  very  base.  Though 
not  recorded  by  previous  workers,  I  found  “pipe  amygdaloids” 
developed  at  the  bottom  of  the  flows  in  several  places  and  at  Taquara 
also  “vesicle  cylinders”  and  “bubble  trains”  set  vertically  in  non- 
vesicular  basalt,  just  as  can  be  instanced  from  the  Stormberg  series.98 

Some  of  the  lavas  are  highly  vesicular  and  even  cavernous,  Brazil 
and  Uruguay  being  noted  for  the  large  quartz-filled  geodes  and  hydro- 
lytes  that  have  become  weathered  out  in  the  red  loamy  soil;  others 
are  very  dense,  in  which  case  there  is  sometimes  a  columnar  structure. 
In  color  they  range  from  black  to  dark  green,  purple,  brown,  red,  or 
chocolate.  Native  copper  is  occasionally  to  be  found  in  them.  The 
thickness  of  the  individual  flows  varies  from  0.5  meter  upward,  the 
general  value  being  probably  anything  up  to  50  meters  or  thereabouts, 
though  Woodworth  has  spoken  of  sheets  from  95  up  to  perhaps  190 
meters  thick  in  the  eastern  part  of  Rio  Grande  do  Sul.  There  are  no 
references  to  the  occurrence  of  thin  layers  of  red  bole  or  earth  between 
successive  effusions,  and  in  this  respect  the  volcanics  are  like  those 
of  South  Africa,  for  which  the  evidence  points  to  the  rapid  welling  out 
of  flow  after  flow  without  any  lengthy  time  interval,  probably  under 
a  dry  climate  such  as  would  have  hindered  the  rapid  weathering  of 
the  lava  crusts. 

As  regards  the  thickness  of  the  group,  Baker99  states  that  in 
different  parts  of  the  basin  figures  of  from  250  to  500  meters  have 
97  Hausen  (1919).  98  Du  Toit  (1907).  99  Baker  (1923),  p.  72. 


GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY  93 

been  measured,  although  much  rock  must  have  been  removed  by 
erosion  from  over  this  great  region.  In  one  of  the  borings  at  Curuzu 
Cuatia,  on  the  lower  Parana  River,  between  Corrientes  and  Concor¬ 
dia,  the  base  of  the  volcanics  (from  which  intercalated  sediments 
were  absent)  was  not  passed  through  at  486  meters  even.  In  this 
respect,  therefore,  the  group  is  comparable  with  the  Stormberg 
basalts,  wherein  a  thickness  of  over  1,000  meters  has  been  recorded 
in  Basutoland  and  400  meters  in  the  Kaokoveld. 

(15)  Petrology 

The  bulk  of  the  flows  are  “melaphyres”  in  which  olivine  is 
absent  or  else  in  small  individuals,  usually  much  altered  to  serpentine, 
or,  as  in  Uruguay  according  to  Walther,  to  iddingsite,  while  the 
structure  is  in  general  ophitic  to  subophitic,  features  that  exactly 
duplicate  those  of  the  Stormberg  volcanics.  Hausen  observed  no 
porphyritic  structures  in  Misiones,  but  Walther  mentions  types 
approaching  the  porphyrites  in  Uruguay,  while  Baker  refers  to 
augite-porphyrite  and  Branner  records  the  presence  of  such  types  in 
Rio  Grande  do  Sul  and  Hussak  in  Santa  Catherina  and  Sao  Paulo. 
This  is  instructive  because,  although  porphyritic  basalts  are  unrep¬ 
resented  in  the  Union  of  South  Africa,  they  appear  occasionally  up 
the  Zambezi-Linyanti  Valley  and  are  well  marked  in  the  Kaokoveld 
of  Southwest  Africa.  Andesitic  varieties  are  sometimes  present  in 
Brazil,  as  at  Santa  Maria. 

Doubtless  the  lavas  issued  mainly  from  fissures,  now  occupied 
by  narrow  vertical  dikes  of  basaltic  or  doleritic  rock,  but  at  Santa 
Maria  what  was  taken  to  be  a  volcanic  neck  was  observed  in  the  face 
of  the  spur  north  of  the  town,  facing  Pedreira  and  overlooking  the 
railway  to  Passo  Fundo.  It  cuts  the  hard  interbedded  sandstone 
capping  the  ridge  and  is  filled  with  a  pale  scoriaceous  rock,  banded  in 
nearly  vertical  fashion  parallel  to  the  wall  of  the  pipe. 

Regarding  the  age  of  the  Serra  Geral  eruptives,  it  can  hardly  be 
doubted  that,  like  those  in  western  Argentina  and  Patagonia,  they 
are  Rhaeto-Liassic,  though  direct  evidence  thereon  is  wanting. 

(16)  The  Intrusive  Dolerites  or  Diabases 

Penetrating  the  strata  of  the  Santa  Catherina  system,  but  more 
commonly  its  lower  half,  are  these  well-known  extensive  sheets  and 
dikes  of  basic  rock  that  are  manifestly  closely  allied  to  the  Serra 
Geral  eruptives,  though,  so  far  as  can  be  gathered,  of  slightly  more 
basic  composition.  Numerous  references  will  be  found  in  the  geolog¬ 
ical  literature  to  such  sills,  but  no  comprehensive  account  thereof. 
Baker  has  indicated  on  his  small-scale  map  the  areas  outside  the 
basin  proper  where  they  have  been  observed  by  him,  and  he  notes 
that  they  also  penetrate  the  basement  formations  in  Paraguay  and 
the  southern  part  of  Matto  Grosso. 

They  are  common  in  the  Itarare,  Bonito,  and  Iraty  beds,  but  the 


94  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

impression  that  I  obtained  from  journeys  between  Porto  Alegre 
through  Santa  Maria  and  Rivera  to  Montevideo,  where  excellent 
sections  are  furnished  by  numerous  railway  cuttings,  was  that  such 
intrusions  were  distinctly  scarce  in  the  upper  part  of  the  system  and 
then  generally  dike-like,  just  as  is  the  case  in  the  Karroo.  Further, 
it  may  be  affirmed  that  the  relative  proportion  of  igneous  rock  is 
much  less  than  in  the  dolerite-riddled  portion  of  the  Union  of 
South  Africa.  Their  precise  relationship  to  the  eruptives  has  not  yet 
been  worked  out,  but  arguing  from  analogy  from  South  Africa1,  they 
would  most  probably  have  been  injected  into  the  framework  of  South 
America  during  or  probably  just  after  the  eruptive  phase,  and  hence 
probably  date  from  the  beginning  of  the  Jurassic. 

They  display  no  unusual  petrological  characters,  ranging  from 
dolerites  without  olivine  to  olivine-dolerites,  and  having  subophitic 
or  ophitic  structures.  A  typical  sample  from  a  bore-hole  near  Rio 
Claro  in  Parana  possessed  a  specific  gravity  of  3.02.  ' 

SECTION  L.  THE  NORTHEASTERN  REGION  OF  BRAZIL 

Mainly  to  Lisboa,2  Crandall,3  and  Small4  is  due  our  knowledge  of 
the  quite  considerable  area  of  Permo-Triassic  in  Maranhao,  Piauhy, 
and  the  northeastern  part  of  Goyaz.  Quite  unjustified  is  its  southerly 
extension,  as  shown  on  Branner’s  geological  map  of  Brazil,  so  as  to 
join  up  with  the  strata  of  the  Parana  basin,  the  formations  filling  the 
broad  gap  being  either  pre-Carboniferous  or  post-Triassic,  though 
probably  the  latter  may  conceal  some  Gondwana  beds. 

The  strata  are  lying  nearly  flat,  resting  on  crystallines,  but  in  the 
east,  according  to  Small,  unconformably  on  the  thick  Serra  Grande 
series,  described  elsewhere  (possibly  of  early  Palaeozoic  age),  and  are 
overlapped  to  the  north  by  the  Cretaceous  and  the  coastal  Tertiaries. 

The  lowest  beds,  of  Permian  age,  make  a  broad,  sweeping  horse¬ 
shoe,  extending  from  the  north  of  the  Pamahyba  River  southward 
through  Piauhy,  then  westward  to  the  Rio  Tocantins  and  down  the 
latter  to  the  borders  of  Para.  The  higher  horizons  lie  within  the 
curve,  the  Triassic  appearing  toward  the  north  and  covering  a 
limited  area  about  the  headwaters  of  the  Mearim  River  in  Maranhao. 

Called  by  Lisboa  the  ‘  ‘  Pamahyba  series  ”  and  divided  by  him  into 
several  groups  totaling  a  few  hundred  meters  in  thickness,  so  far  as 
one  can  gather,  the  beds  consist  successively  of  gray  calcareous  shales 
and  gray  to  white  sandstones,  a  thick  red  sandstone  having  purple 
spots  and  with  pisolitic  limestone,  a  gray  sandstone  followed  by  green 
and  chocolate  shales,  and  limestones  with  cherty  bands.  Glacial 
signs  are  absent  at  the  base.  Psaronius  associated  with  gymno- 
spermous  wood  has  been  found  in  many  localities  in  this  wide  region 
throughout  the  full  thickness  of  strata,  together  with  the  cast  of  a 
stem  referred  to  Sigillaria  in  Piauhy.  Since  the  first-named  occurs, 

1  Du  Toit  (1920).  2 Lisboa  (1914).  3 Crandall  (1910).  4  Small  (1914). 


GONDWANA  SYSTEM  IN  BRAZIL,  URUGUAY,  AND  PARAGUAY  95 

according  to  Derby,  in  Sao  Paulo  State  associated  with  Stereosternum 
and  Lycopodiopsis,  such  would  suggest  that  the  Parnahyba  series 
probably  represents  horizons  from  about  the  Iraty  upward  and  hence 
mainly  of  Permian  age,  the  beds  being  all  of  fresh-water  origin, 
apparently. 

The  succeeding  “Mearim  series”  consists  of  a  few  hundred 
meters  of  white,  splotched,  and  red  sandstones  overlain  by  flow’s  of 
basic  amygdaloidal  lavas,  which  are  also  intercalated  in  the  red 
sandstones,  the  strata  building  table-topped  hills,  well  represented 
between  Grajahu  and  Pastos  Bons,  while  they  and  the  underlying 
beds  are,  furthermore,  cut  by  intrusive  dolerite  in  the  form  of  sheets 
and  dikes. 

There  can  be  no  doubt  that  this  upper  series,  older  than  the 
Cretaceous  and  so  like  the  Sao  Bento  of  southern  Brazil,  is  of  Triassic 
age,  support  for  which  is  found  in  the  discovery  of  scales  of  Semio - 
notus  near  Floriano  on  the  Parnahyba  River. 

Attention  might  furthermore  be  directed  to  the  general  parallel¬ 
ism  in  facies  with  the  ‘  ‘  Karroo  ”  succession  of  the  Low'er  as  contrasted 
with  the  Upper  Congo  basin  in  Africa,  namely,  in  the  absence  of 
glacials,  the  shaly  and  often  slightly  calcareous  character  of  the 
Lualaba  beds  with  fish  and  crustacean  remains,  and  the  succeeding 
yellow  or  pink  friable  Lubilache  beds,  though  volcanic  rocks  are  not 
known  to  overlie  the  latter. 

SECTION  M.  EASTERN  BRAZIL 

In  the  coastal  region  of  Bahia  and  Sergipe,  Branner 5  has  described 
under  the  name  of  the  “Estancia  beds”  certain  strata,  which  he 
placed  in  the  Permian,  that  occupy  the  region  from  Bahia  nortlrward 
to  the  Rio  Sao  Francisco,  though  much  concealed  by  Cretaceous  and 
Tertiary  formations.  Subsequently  Soper 6  has  removed  a  part  of  this 
to  the  Cretaceous  and  has  furthermore  stated  that  the  Estancia  beds 
pass  down,  apparently  wdthout  a  break,  into  a  thick  series  of  rocks 
that  rest  unconformably  upon  an  uneven  surface  of  crystallines  and 
proterozoic  (?)  quartzites.  It  totals  no  less  than  3,700  meters,  the 
beds  being  tilted  and  sometimes  considerably  disturbed,  and  even 
faulted,  the  foldings  trending  generally  a  little  east  of  north,  but 
along  other  axes  as  w^ell,  overlain  discordantly  by  gently  inclined 
Cretaceous  and  by  horizontal  Tertiaries. 

In  the  lowrer  part  are  seen  shales,  slates,  and  gray  to  pink  lime¬ 
stones,  followed  by  a  great  mass  of  green,  blue,  dark  or  dark  red,  often 
micaceous,  shales,  succeeded  by  red  sandstones  and  by  blue  lime¬ 
stones.  The  finding  of  Alethopteris  branneri  White  in  a  dark  shale 
beneath  red  Cretaceous  sandstone  at  Aracy,  and  according  to  Leme 7 
of  Psaronius  near  to  Conselho,  would  suggest  an  upper  Carbonifer¬ 
ous  or  more  likely  a  lowrer  Permian  age  for  the  upper  part  of  the  series; 

6Branner  (1913).  6Soper  (1914),  pp.  25-37.  7Leme  (1924),  p.  181. 


96  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

consequently  the  basal  portion  may  extend  well  back  into  the 
Carboniferous. 

Comparisons  may  be  instituted  with  the  gently  tilted  formations 
in  the  western  part  of  the  Belgian  Congo,  particularly  the  middle 
portion  of  the  Kundulungu,  called  by  Cornet  the  “Mpioka  series,  ” 
with  its  red  coloration. 

It  is  just  possible  that  the  horizontal  limestones  and  shales  of  the 
Salitre  Valley  in  Bahia,  extending  over  wide  areas  to  the  southwest 
thereof,  resting  unconformably  upon  much  older  formations,  and 
tentatively  placed  by  Branner8  in  the  Permian,  may  belong  to  the 
Estancia  series,  but  palaeontological  data  are  essential  before  any 
further  advances  can  be  made.  In  the  coastal  zone  to  the  south  of 
Bahia  near  Cannavieiras  beds  occur  on  the  Rio  Pardo  and  Rio 
Jequitinhonha  that  have  yielded  plants  referred  by  Hartt  to  Aster o- 
phyllites  (?)  scutigera,  suggested  by  D.  White  as  perhaps  a  Phyllo- 
theca.9 

Nevertheless,  the  following  important  points  have  been  estab¬ 
lished:  (i)  The  presence  of  some  undoubted  late  Palaeozoic  continen¬ 
tal  beds  in  the  coastal  region;  (2)  their  partially  calcareous  nature; 
and  (3)  their  disturbance  by  early  mesozoic  movements  not  alto¬ 
gether  coinciding  in  trend  with  the  ancient  “Brasilides,  ”  the  signifi¬ 
cance  of  which  will  be  remarked  on  in  Chapter  VI. 

SECTION  N.  THE  CRETACEOUS  OF  THE  INTERIOR 

Brief  reference  only  will  be  made  to  the  continental  Bauru  beds 
of  Sao  Paulo  State  that  rest  horizontally  and  unconformably  on  the 
Triassic  traps  and  are  probably  of  Cretaceous  age.  Their  precise 
distribution  being  not  very  well  known,  these  beds  are  not  indicated 
on  the  accompanying  geological  map,  but  it  might  be  remarked  that 
they  occupy  wide  areas,  forming  much  of  the  higher  ground  border¬ 
ing  the  Parnahyba,  Rio  Grande,  Tiete,  and  Paranapanema,  and 
extend  down  the  valley  of  the  Parana  to  Guayra,  while  beyond  at 
San  Ignacio  near  Posadas  the  sandstones  have  been  brought  down  to 
river-level  by  warping.  The  transgressive  base  is  indicated  by  the 
fact  that  they  rest  on  the  traps  between  Bauru  and  Agudos,  but  on 
the  Triassic  sandstone  at  Botucatu.  They  are  composed  chiefly  of 
massive  and  often  false-bedded  white  to  red  sandstones  with  a  cal- 
careo-argillaceous  cement.  Farther  north  they  form  a  broad  covering 
along  and  west  of  the  Rio  Sao  Francisco,  known  here  as  the  “Pira- 
pora  sandstone,  ”  and  appear  to  connect  up  with  the  slightly  younger 
but  marine  Cretaceous  of  rather  similar  character  of  Piauhy  and 
Ceara.  These  beds  rest  very  largely  upon  a  peneplain  cut  across  the 
underlying  formations  of  Brazil,  and  thus  reveal  the  very  consider¬ 
able  denudation  of  the  continent  during  the  Jurassic  epoch. 

8Branner  (1913),  p.  626;  (1919)  p.  237;  Crandall  (1919),  p.  244.  9  White  (1908),  p.  423. 


CHAPTER  VI 


GEOLOGICAL  HISTORY  OF  THE  AFRO-AMERICAN 

LAND  MASS 

That  these  two  continents  were  intimately  connected  during 
several  geological  epochs  will,  I  venture,  be  acknowledged  after  the 
perusal  of  the  preceding  pages,  though  the  manner  of  such  union 
would  admittedly  be  speculative.  In  preparing  this  review  an 
attempt  was  made  first  of  all  to  write  the  historical  account,  irrespec¬ 
tive  of  any  hypothesis  as  to  the  manner  of  such  union  or  of  the 
ultimate  mode  of  separation  of  the  land-masses  though  it  became  evi¬ 
dent,  as  the  data  were  assembled,  that  they  pointed  very  definitely  in 
the  direction  of  the  displacement  hypothesis,  and  that  they  could 
most  satisfactorily  be  interpreted  in  the  light  of  that  brilliant 
conception. 

It  was  finally  decided  to  treat  the  subject  from  this  viewpoint 
rather  than  from  any  other,  but  only  in  such  a  way  as  to  bring  out 
particular  features  the  significance  of  which  would  otherwise  be 
overlooked;  the  hypothesis  itself  could  then  be  discussed  indepen¬ 
dently  and  without  prejudicing  this  particular  chapter. 

THE  SILURO-DEVONIAN 

Knowledge  concerning  the  early  limits  of  the  Afro-American 
mass  only  becomes  definite  during  the  late  Silurian,  when  the  ocean 
must  have  covered  the  central  Sahara,  western  Africa,  the  lower 
portion  of  the  Amazon  Valley,  parts  of  Bolivia,  Jachal,  San  Juan,  and 
Mendoza,  but  not  the  Nevado  de  Famatina.  The  faunas  up  to 
the  very  close  of  that  epoch  were,  it  is  essential  to  note,  boreal  in 
their  aspect. 

Attention  has  more  especially  to  be  focussed  on  far  distant 
Bolivia,  because  of  the  light  which  its  splendidly  developed  lower 
Palaeozoics  shed  on  the  precise  age  of  the  unfossiliferous  sandstone 
formations  of  Parana  and  the  Cape,  customarily  ascribed  to  the 
lower  Devonian.  The  valuable  accounts  of  the  stratigraphy  of  this 
country  by  d’Orbigny,10  Steinmann,11  Ulrich,12  Knod,13  and  others, 
supplemented  recently  by  Kozlowski14  and  Bonarelli,15  clear  up 
many  points,  although  showing  the  need  for  further  investigation. 

Following  Knod  and  Kozlowski,  the  normal  Bolivian  succession, 
resting  usually  on  the  Ordovician,  is  divisible  into:  (i)  The  lower  or 
Ida  sandstone,  about  170  meters  thick,  with  unfossiliferous  lower 

10D’Orbigny  (1842).  12 Ulrich  (1893).  14 Kozlowski  (1923). 

11  Steinmann  (1904).  13  Knod  (1908).  15  Bonarelli  (1921),  pp.  39-56. 

97 


98  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

half  (a  greenish  gray  or  whitish  quartzose  sandstone  overlain  by 
gray  calcareous  sandstone  and  calcareous  flagstone;  (2)  the  Conu- 
laria  and  Crinoid  beds  some  200  meters  thick  (dark  shales  and  sandy 
shales  with  calcareous  nodules,  like  those  of  Parana) ;  (3)  the  upper 
or  Huamampampa  sandstone  up  to  250  meters  thick  (grayish  and 
unfossiliferous) .  These  700  to  800  meters  of  beds  are  generally 
agreed  upon  as  representing  the  lower  Devonian  alone  (Oriskany), 
but  Kozlowski  has  stated  that  around  Lake  Titicaca  there  is 
(4)  the  Sicasica  formation  (quartzites  of  a  warm  color,  micaceous 
brown  or  white  shales  with  sandy  layers  and  black  siliceous  nodules) , 
with  a  fauna  showing  middle  Devonian  forms  together  with  a  few 
lower  Devonian  types  followed  by  unfossiliferous  sandstones  and 
shales — Onondaga-Hamilt  on . 

Now,  both  in  Parana  and  the  Cape  the  sequence  is  almost  identi¬ 
cal,  the  barren  Furnas  and  Table  Mountain  sandstones  being  respec¬ 
tively  followed  by  the  dark  fossiliferous  Pont  a  Grossa  and  Bokkeveld 
shales,  which  are  unquestionably  equivalent  to  the  Conularia  and 
Crinoid  shales  of  Bolivia,  as  borne  out  by  their  particular  faunas. 

On  the  other  hand,  Kozlowski16  and  Bonarelli17  have  independ¬ 
ently  pointed  out  that  in  parts  of  Bolivia  this  important  system 
actually  includes  in  its  basal  section  strata  that  belong  to  the  upper¬ 
most  Silurian,  and  which,  although  of  no  great  thickness,  are  wide¬ 
spread  to  the  north  and  southeast  of  Sucre,  being  characterized  by 
the  presence  of  Clarkeia  antisiensis  ( Liorhynchus  bodenbenderi )  and 
several  other  forms  not  found  associated  with  the  typical  Devonian 
faunas.  At  Tarabuco,  east-southeast  of  Sucre,  the  succession  resting 
upon  the  Ordovician  consists  of  40  meters  of  barren  white  quartzite, 
30  meters  of  yellow  to  red  sandstones  with  Clarkeia ,  overlain  by  some 
hundreds  of  meters  of  yellowish  sandy  shales,  in  the  upper  part  of 
which  fossils  characteristic  of  the  Icla  shales  occur;  at  Finca  Con¬ 
st  ancia  to  the  north  of  Sucre  a  rather  similar  order  can  be  seen.  That 
is  to  say,  where  the  normally  unfossiliferous  basal  group  of  whitish 
quartzitic  sandstones  has  developed  a  marine  facies,  the  latter  now 
carries  not  Devonian  but  Silurian  forms,  wherefore  the  presumption 
is  strong  that  the  basal  part  of  the  equivalent  Furnas  and  Table 
Mountain  sandstone  is  in  each  case  of  uppermost  Silurian  age.  It  is 
significant  that  the  only  molluscan  remains  yet  found  in  the  Cape 
formation — unfortunately  not  identifiable — should  occur  at  the 
very  base  of  the  sandstone. 

A  parallel  is  forthcoming  from  Jachal,  where  Keidel,18  studying 
the  unbroken  succession  in  the  Lomas  de  los  Piojos,  has  recorded  the 
zone  with  Clarkeia  antisiensis  and  Monograptus  priodon,  composed  of 

“Kozlowski  (1923),  pp.  8-10. 

“Bonarelli  (1921),  pp.  46-53. 

18 Keidel  (1921),  pp.  32-37,  51-54;  Clarke  (1913),  P-  332. 


GEOLOGICAL  HISTORY  OF  THE  AFRO-AMERICAN  LAND  MASS  99 


green  and  dark  micaceous  shales,  which  are  followed  by  800  meters  of 
“Devonian,”  the  basal  500  meters  being  unfossiliferous  sandy 
shales,  greenish  and  bluish  gray  sandstones  with  dark  sandstone  ribs, 
followed  by  similar  gray  and  green  beds,  but  with  the  typical  forms 
of  the  “austral”  Devonian  of  Bolivia,  Parana,  Falklands,  and  Cape. 

THE  DEVONIAN  OSCILLATIONS 

These  illuminating  sections  in  Bolivia  prove,  therefore,  that  the 
great  “Devonian”  transgression  really  began  just  prior  to  the  close 
of  the  Silurian.  At  that  period  Central  Africa  had  been  land  probably 
as  far  northward  almost  as  Nigeria  and  southward  right  to  the  Cape, 
while  most  of  eastern  and  southern  Brazil,  Uruguay,  southeastern 
Bolivia,  and  northern,  central,  and  eastern  Argentina  were  bound 
to  that  continent. 

Along  the  margins  of  this  land-mass  were  then  accumulated  the 
siliceous  deltaic  deposits  of  Parana,  Matto  Grosso,  Sierra  de  la 
Ventana,  the  Falklands,  and  the  Cape  (from  Clan  william  in  the 
west  to  Zululand  in  the  east),  while,  as  the  ocean  advanced  and  the 
area  of  this  section  of  Gondwanaland  decreased,  the  delta  fringe 
crept  inward  and  marine  muds  and  sands  with  a  lower  Devonian 
fauna  of  austral  type  came  to  be  laid  down  on  them.  In  Africa,  the 
Gold  Coast  region  was  ultimately  submerged,  and  in  the  opposite 
direction  the  southern  third  of  the  Cape  and  the  whole  of  the  Falk¬ 
land  Islands;  whether  the  Cordoba-San  Luiz  region  remained  as 
an  island  is  unknown,  but  certainly  Jachal  and  Salta  were  inundated, 
though  probably  not  the  Famatina,  Puna  de  Atacama,  or  the  center 
of  La  Rioja. 

A  cool  climate  is  expressly  indicated  by  the  glacial  zone  of  the 
Table  Mountain  series,  and  indirectly  by  the  dark  gray,  blue,  and 
green  coloring  of  the  marine  strata,  by  the  absence  of  limestones,  and 
scarcity  of  corals  in  them;  everywhere  a  shallow  ocean  has  to  be 
postulated,  which  would  explain  the  widespread  transgression  of  its 
waters  in  certain  territories. 

THE  DEVONIAN  FAUNAS 

With  the  lower  Devonian,  for  reasons  not  yet  understood,  came 
strong  faunal  differentiations.  The  boreal  element  still  predominates 
in  the  Sahara,19  as  shown  by  species  from  Rhineland  and  North 
America,  but  an  austral  bias  is  signaled  by  such  forms  as  Homolo- 
notus  herscheli ,  Leptocoelia  flabellites,  Spirifer  rousseauxi ,  etc.  The 
Maecuru  (Amazon)  assemblage,  while  showing  alliances  with  the 
European,  displays  the  North  American — Oriskany-Onondaga — 
facies,  but  the  austral  element  is  nevertheless  quite  marked  in  certain 

19Haug  (1905);  Lemoine  (1913),  p.  19. 


100  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

groups,  particularly  among  the  trilobites,  with  peculiarities  among 
the  brachiopods,  e.g.,  the  Spirifers,  which  are  more  marked  still  in 
the  Bolivian  and  west  Argentine  areas.  The  fauna  of  Matto  Grosso 
is  not  far  removed  from  that  of  Bolivia,  but  the  west  Argentine  one 
again  stands  apparently  closer  to  that  of  the  Falklands  than  to 
Parana.  Clarke 20  has  commented  on  the  fact  that  the  Falkland  fauna 
is  much  closer  allied  to  the  Bokkeveld  of  the  Cape  than  to  the  South 
American  assemblages,  peculiar  only  so  long  as  one  disregards  the 
doctrines  of  the  displacement  hypothesis,  for  under  the  latter  these 
islands  would  have  been  nearer  geographically  to  South  Africa  than 
to  Brazil.  We  know  that  some  high  ground  must  have  lain  in  early 
Devonian  times  to  the  west  and  northwest  of  the  Cape  (sufficient  to 
support  local  glaciers) ,  while  the  sources  of  the  siliceous  formations  of 
Sierra  de  la  Ventana  and  Parana  probably  lay  to  the  east  rather  than 
the  west.  Consequently  the  Parana  region  might  well  have  occupied 
an  embayment  with  a  promontory  intervening  between  the  Brazilian 
and  Falkland  shore-lines. 

Our  knowledge  concerning  much  of  the  periphery  of  Gondwana- 
land  ceases  with  the  lower  Devonian,  but  during  the  mid-Devonian 
the  ocean  persisted  in  the  Amazon  region  and  in  northern  Bolivia. 
The  Brazilian  Erere  fauna  shows  increased  affinities  with  the  North 
American,  in  addition  to  forms  from  the  Maecuru,  but  it  also  has 
alliances  with  the  Sicasica  fauna  of  Bolivia  through  such  forms  as 
Tropidoleptus  carinatus  and  Homolonotus  dekayi ,  typically  Hamilton 
species,  the  latter  represented  also  in  Gold  Coast  Colony.21  In  Ahnet 
(Sahara)  the  mid-Devonian  carries  Agoniatites  vanuxemi ,  characteris¬ 
tic  of  the  Marcellus  stage  of  New  York,  while  the  upper  Devonian  of 
Tassili  shows  affinities  with  North  America.  Faunas  of  late  Devonian 
age  are  not  yet  known  in  South  America  outside  of  the  Amazon 
Valley. 

y  THE  CARBONIFEROUS  EPOCH 

The  oscillating  shallow  seas  then  withdrew — probably  the  conti¬ 
nent  rose  isostatically — for  in  South  Africa,  the  Falklands,  and  the 
Sierra  de  la  Ventana  area  siliceous  estuarine  and  fluviatile  beds  of 
presumably  upper  Devonian-lower  Carboniferous  age  (derived  in 
the  first-named  from  the  erosion  of  the  old  Devonian  land-mass) 
succeed  the  marines  with  but  a  few  plant  remains.  At  Paracas  on 
the  coast  of  Peru  are  the  only  other  known  plant-bearing  strata, 
probably  of  middle  Carboniferous  age. 

Only  in  southern  Peru,  a  little  north  of  Lake  Titicaca,22  are  marine 
beds  represented  in  South  America,  of  undoubted  lower  Carbonifer¬ 
ous  (Avonian)  age,  though  present  in  Gold  Coast  Colony  and  the 
Sahara,  and  it  would  appear  that  the  ocean  then  retreated  to  beyond 

20  Clarke  (1913),  pp.  13,  56.  21Kitson  (1925).  22  Douglas  (1920). 


GEOLOGICAL  HISTORY  OF  THE  AFRO-AMERICAN  LAND  MASS  101 

its  limits  during  the  Silurian,  thus  presenting  an  increased  area  of 
land  to  erosion.  A  certain  amount  of  folding  occurred  in  the  pre- 
Andine  regions  about  this  time,  seemingly  with  the  injection  of 
granites  in  Peru  and  Bolivia. 

With  the  upper  Carboniferous  came  a  return  of  the  ocean,  which 
entered  the  lower  Amazon  region  and  occupied  a  large  part  of  Peru 
and  Bolivia,  but  the  block  between  the  Puna  de  Atacama  and  Potosi 
remained  land,  around  which  a  gulf  of  the  sea  must  have  crept  to 
penetrate  into  the  western  part  of  San  Juan  and  parts  of  Chile  on 
about  the  same  parallel  of  latitude ;  all  the  country  to  the  northeast, 
east,  and  southeast  of  San  Juan  probably  remained  unsubmerged. 

The  upper  Carboniferous  occurs  on  either  side  of  the  Amazon 
River  with  wide  extension — a  group  of  limestones,  shales,  and  sand¬ 
stones,  perhaps  600  meters  thick,  with  an  abundant  fauna,  including 
Productus  cor  a ,  P.  semireticulatus,  Athyris  subtilita,  Spirifer  earner a- 
tus ,  etc.,  allied  to  the  upper  Carboniferous  of  the  United  States  and 
Urals  and  showing  resemblances  to  the  Carboniferous  of  Bolivia  and 
Peru  on  the  one  hand  and  of  the  Sahara  on  the  other.  Most  curiously, 
as  Doctor  Reed  has  well  pointed  out,  the  equivalent  fauna  from 
Barreal  is  quite  distinct  from  those  recorded  elsewhere  in  North  or 
South  America,  the  forms  being  nearly  all  either  closely  allied  to  or 
comparable  with  established  species  from  the  lower  Carboniferous  of 
Europe  or  the  middle  or  upper  Carboniferous  of  Russia  or  parts  of 
Asia.  Probably,  therefore,  the  western  part  of  San  Juan  was  not  in 
direct  communication  with  the  ocean  to  the  north.  The  fauna,  it 
might  be  noted,  displays  no  affinities  with  those  of  eastern  or  west¬ 
ern  Australia. 

THE  CARBONIFEROUS  GLACIATION 

Time  is  revealing  more  and  more  the  number  of  places  where  the 
/  Carboniferous  glaciers  passed  into  a  shallow  ocean  and,  melting, 
I  dropped  their  burden,  for  example  in  Tasmania,  New  South  Wales, 
Western  Australia,  the  Salt  Range  in  India,  the  San  Juan  district  in 
Argentina,  and  Parana  in  Brazil.  It  has  furthermore  become  evi¬ 
dent  that  over  wide  areas  the  ice  must  have  traveled  across  a  gently 
undulating  surface  nearly  at,  if  not  below,  sea-level,  as  is  proved  by  the 
shales  with  marine  mollusca  in  Parana  and  Southwest  Africa,  by  the 
Dwyka  shales  of  South  Africa,  Bonito  coal  measures  of  Brazil,  etc. 
The  general  low  relief  of  the  ice-ridden  territory  is  indeed  one  of  the 
most  unexpected  peculiarities  of  this  Palaeozoic  glaciation. 

I  have  adduced  evidence  to  show  that  in  South  Africa23  the  glaci¬ 
ation  apparently  started  at  several  centers,  in  each  case  over  some¬ 
what  higher  ground,  but  that  the  ice-sheets  at  the  maximum  stage  of 
glaciation  seem  to  have  coalesced,  to  discharge  southward  into  a 


23  Du  Toit  (1921). 


102  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

body  of  probably  fresh  water.  An  important  center  was  situated  in 
Southwest  Africa,  but  it  is  not  at  all  unlikely  that  a  similar  feature 
lay  to  the  northwest  or  even  west  of  the  Cape  (from  which  direction 
had  indeed  come  the  local  glaciers  of  the  Devonian) ,  suggestive  being 
the  “boulder  pavement”  at  Eland’s  Vlei  on  the  Doom  River,  with 
its  groovings  directed  nearly  west-east. 

In  South  America  the  evidence  consistently  favors  an  ice  center 
situated  out  in  the  present  Atlantic,  the  significance  of  which  will  be 
appreciated  from  the  study  of  Figure  7.  The  position  allotted  to  the 
Falkland  Islands  in  this  geographical  scheme  is  determined  approxi¬ 
mately  by  a  series  of  rather  pretty  comparisons:  (1)  The  folding  is 
along  two  axes,  one  directed  west-northwest  and  the  other  at  right 
angles  thereto,  but  of  fairly  open  character  as  a  rule,  with  dips  else¬ 
where  generally  low  over  wide  areas,  and  thus  comparable  with  the 
Ceres-Clanwillian  region,  and  neither  with  the  Caledon-Riversdale 
sections  nor  with  Argentina,  where  the  first-mentioned  set  of  foldings 
is  dominant  and  intense;  (2)  the  lower  Devonian  sandstones  are 
gritty  and  pebbly,  as  in  the  Cape-Clanwilliam  region  or  in  Parana, 
and  not  quartzitic,  as  in  Mossel  Bay  or  in  the  Sierra  de  la  Ventana, 
moreover,  the  glacial  horizon  of  the  western  Cape  may,  according  to 
Baker,  just  possibly  be  represented  in  West  Island;  (3)  the  fauna  of 
the  Devonian  shales  in  the  Falklands  is  very  closely  related  to  that 
of  the  Bokkeveld,  less  so  to  that  of  Parana ;  (4)  the  Devono-Carbonif- 
erous  quartzites  of  the  Falklands  are  identical  with  the  Witteberg 
series  of  the  Cape  and  not  closely  comparable  with  the  greywacke 
phase  of  the  Sierra  de  la  Ventana;  (5)  the  strongly  cleaved  tillite  of 
the  islands  is  slightly  disconformable  to  these  quartzites,  as  in  Clan- 
william,  whereas  the  glacials  of  the  Rio  Sauce  Grande  are  conform¬ 
able  to  the  strata  below,  just  as  in  the  south  of  the  Cape  (Worcester) ; 

(6)  the  tillite  is  of  great  thickness,  with  some  intercalated  shales,  and 
hence  like  that  of  the  southern  Karroo  and  the  Rio  Sauce  Grande; 

(7)  the  Lafonian  sandstone,  just  above  the  tillite,  has  no  lithological 
representative  in  the  Cape,  but  finds  its  equivalent  in  the  Itarare 
series  of  Uruguay  and  Brazil;  (8)  the  absence  of  the  “ Mesosaurus 
zone”  links  the  islands  with  Argentina;  (9)  the  great  development 
of  Lafonian  sediments  devoid  of  coals  recalls  the  facies  of  the  Sierra 
de  Pillahuinco  and  the  Karroo  of  the  southern  Cape  rather  than  that 
of  the  northern  Karroo  or  of  Parana;  (10)  the  upper  Lafonian  beds 
show  lithological  resemblances  with  the  upper  Karroo  and  not  the 
Triassic  of  South  America;  (11)  the  few  dolerite  intrusions  suggest 
again  the  Cape-Clanwilliam  region. 

If  we  admit  the  displacement  hypothesis,  these  affinities  would 
collectively  assign  the  Falklands  to  a  position  along  the  northern 
edge  of  the  broad  belt  of  foldings  that  linked  the  Cape  with  Argen¬ 
tina,  but  would  place  them  somewhat  nearer  to  Africa.  Despite  the 


GEOLOGICAL  HISTORY  OF  THE  AFRO-AMERICAN  LAND  MASS  103 

fact  that  these  islands  rise  from  the  Patagonian  coastal  shelf,  and 
that  the  late  Mesozoic  foldings  (Patagonides)  strike  southeastward 
near  the  Gulf  of  San  Jorge,  and  therefore  toward  them,  as  remarked 
by  Windhausen,24  the  Falklands,  if  we  ignore  the  mere  tectonic 
parallelism,  display  not  the  slightest  affinities  with  Patagonia,  where 
the  late  Triassic  volcanics  and  sediments  rest  upon  the  crystallines, 
with  no  representatives  of  the  Palaeozoics.  It  must  accordingly  be 
concluded  that  this  outpost  of  Gondwanaland  belongs  to  the  north¬ 
east  rather  than  to  the  west  and  actually  affords  very  striking  sup¬ 
port  to  the  displacement  hypothesis.  The  record  by  Schwarz  of 
granite,  probably  from  volcanic  ejectamenta,  in  Tristan  da  Cunha  is 
an  indication  of  crystalline  plutonics  underlying  part  of  the  South 
Atlantic  basin. 

The  north-south  directed  groovings  beneath  the  tillite  in  the 
Falklands  would  lend  a  modicum  of  support  to  such  an  hypothetical 
ice-center  situated  out  in  the  Atlantic,  though  impinging  on  Brazil, 
as  indicated  by  the  common  absence  of  the  glacials  in  the  southern 
corner  of  that  country,  by  the  fluvio-glacials  in  Santa  Catherina, 
Uruguay,  and  San  Juan,  and  the  marine  glacials  in  Parana  and  near 
Barreal  in  San  Juan.  The  conditions  in  Goyaz  and  Matto  Grosso  are 
not  yet  known,  while  it  is  uncertain  that  ice  formed  at  this  date  in 
Bolivia,  since  the  glacials  of  the  Bermejo  series  may  perhaps  be  of 
Permian  age. 

In  1 92 1 ,25 1  ventured  to  point  out  that  the  evidence  in  South  Africa 
favored  the  deduction  that  the  several  centers  had  become  glaciated 
in  turn,  the  earliest  on  the  west,  the  latest  on  the  east.  Both  in  New 
South  Wales  (Seaham  area)  and  in  San  Juan  Rhacopteris  and  Car  diop¬ 
ter  is  are  present  between  the  lowermost  glacials,  while  such  is  not  the 
case  in  Brazil,  South  Africa,  India,  Victoria,  or  Tasmania.  Although 
the  palaeontological  evidence  on  all  these  points  is  not  as  definite  as 
could  be  desired,  it  would  appear  that  glaciation  commenced  in  the 
middle  or  early  upper  Carboniferous  in  the  Southern  Hemisphere  in 
the  Seaham  area,  extended  to  Argentina,  then  to  South  Africa,  to  the 
west  of  Australia,  Tasmania,  and  India  during  the  upper  Carbonifer¬ 
ous,  and  recurred  during  the  early  Permian  in  New  South  Wales 
and  perhaps  still  later  in  Bolivia  and  the  eastern  Congo. 

Under  the  displacement  hypothesis,  not  only  would  all  the  areas 
affected  be  brought  together  in  the  most  simple  manner,  within  an 
oval  perhaps  no  larger  than  the  African  continent,  but  the  non¬ 
synchronism  of  glaciation  in  the  several  parts  would  find  their 
explanation  as  the  natural  outcome  of  an  extensive  active  ice-cap, 
the  margins  of  which  progressively  advanced  in  one  direction  and 
retreated  in  the  other,  so  that  with  time  the  sheet  had  as  a  whole 
migrated  over  the  surface,  glaciating  various  sections  in  turn,  exactly 

24  Windhausen  (1921a),  p.  6.  26  Du  Toit  (1921). 


104  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

as  seems  to  have  been  the  case  with  the  Pleistocene  Ice  Age  in  the 
Northern  Hemisphere.  This  view  would  perhaps  meet  Coleman’s 
well-founded  criticism  of  the  excessive  size  of  the  single  ice-cap  under 
this  supposition.26 

The  causes  of  this  intense  refrigeration,  lasting  through  about 
an  entire  geological  epoch,  are  still  largely  speculative,  but  some 
additional  suggestions  may  be  thrown  out.  I  had  tentatively 
advanced  the  hypothesis  of  “eccentric  ice-capping”  to  explain  the 
growth  and  migration  of  ice  centers,  but  a  second  aspect,  not  yet 
brought  forward,  is  a  possible  variation  in  the  crustal  heat  of  the 
earth  locally,  all  explanations  having  hitherto  sought  for  such  causes 
outside  the  lithosphere.  Admitting  the  probability  of  Joly’s  theory 
of  the  connection  between  radioactivity  and  diastrophism,  it  would 
follow  that  periods  of  liquefaction  of  the  subcrust  and  the  abnormally 
rapid  escape  of  internal  heat  by  volcanism  and  hypabyssal  injection 
would  be  succeeded  by  intervals  of  quiescence,  endothermic  reac¬ 
tions,  and  reduced  heat  transference.  A  certain  section  of  the  crust 
might  thereupon  come  to  have  over,  a  period  an  exceptionally  low 
geothermic  gradient,  under  which  refrigeration  would  at  least  be 
facilitated,  provided  that  climatic  and  other  well-recognized  predis¬ 
posing  agencies  were  concurrently  present.  That  the  entire  crust 
of  the  globe  should  have  been  simultaneously  affected  in  any  such 
manner  is,  however,  almost  unthinkable. 

CARBO-PERMIAN  SEDIMENTATION 

During  the  closing  stages  of  glaciation,  the  upper  Carboniferous 
ocean,  with  its  characteristic  Spirifer  and  Productus  fauna,  occupied 
the  Amazon  region,  Peru,  and  Bolivia,  and  penetrated  into  the 
western  part  of  the  San  Juan.  In  some  extraordinary  fashion,  the 
remarkable  Eurydesma  fauna  of  the  Salt  Range  and  Hunter  River 
area  makes  its  appearance  in  Southwest  Africa,  though  by  what 
channel  this  specialized  lamellibranch  form  reached  this  spot  is 
unknown,  but  presumably  via  the  Cape,  for  a  route  across  Africa 
from  Mozambique,  while  not  yet  proved  impossible,  is  rather  unlikely. 

In  southern  Brazil,  Uruguay,  Paraguay,  and  western  Argentina 
deltaic  deposits  were  laid  down,  the  “ Glossopteris  flora”  flourished, 
and  the  coals  of  Brazil  were  formed;  the  areas  marginal  thereto 
received  estuarine,  lacustrine,  or  “basin”  deposits,  for  example  the 
Cape,  Southwest  Africa,  and  eastern  Argentina.  A  deepening  of  the 
waters  then  drowned  these  deltaic  or  shallow-water  deposits,  except 
in  western  Argentina,  Bolivia,  and  Africa  north  and  east  of  the  Cape, 
in  which  directions  the  ground  presumably  stood  higher,  and  within 
this  immense  area  of  open  water  the  black,  sulphureted,  and  often 
limy  muds  of  the  Iraty-upper  Dwyka  shales  were,  as  suggested  by 

26Coleman  (1926),  p.  260. 


GEOLOGICAL  HISTORY  OF  THE  AFRO-AMERICAN  LAND  MASS  105 

the  writer,  deposited  in  an  estuary  or  land-locked  sea  like  the  Gulf  of 
Bothnia.27  The  deeper,  sulphureted  waters  were  unfavorable  to 
bathyal  life  and  almost  the  only  forms  were  fishes,  the  swimming 
Mesosaurus ,  and  Crustacea.  The  development  of  bedded  limestones 
in  Sao  Paulo  indicates  communication  in  that  direction  with  the 
northern  Permo-Carboniferous  ocean — a  broad  region  of  marine 
deposition  in  the  Triassic  after  an  intervening  period  of  elevation 
and  erosion. 

In  Natal,  Transvaal,  and  Rhodesia28  deltaic  coal  measures  were 
laid  down  on  an  extensive  scale,  into  which  crept  a  few  relics  of  the 
northern  flora,  introduced  presumably  by  way  of  Brazil,  though  fail¬ 
ing  to  reach  Rhodesia  or  India.  In  the  west  and  south  of  the  Cape,  in 
the  Falklands,  and  in  eastern  Argentina  the  deposits  were  of  the  kind 
called  “basin”  by  the  writer  for  want  of  a  better  term — a  monoto¬ 
nous  succession  of  fine  sands  and  silts,  often  ill-differentiated,  with 
occasional  “marls”  and  calcareous  nodules,  laid  down  on  interior 
plains  or  in  very  wide  and  shallow  depressions  subject  to  flooding  and 
desiccation  like  those  of  Turkestan.  The  conditions  were,  however, 
favorable  for  vertebrate  life,  as  shown  by  the  wonderful  reptilian  and 
amphibian  fauna  of  the  Beaufort  beds  of  southern  Africa,  the  forms 
appearing  earliest  in  the  southwestern  comer  of  the  Karroo  and 
spreading  thereafter  to  the  northeast,  through  East  Africa  to  Mada¬ 
gascar,  India,  and  even  Russia,  accompanied  by  members  of  the 
Glossopteris  flora. 

THE  PERMO-TRIASS1C  MOVEMENTS 

Hitherto  crustal  movements  had  been  mild  and  generally  in  the 
vertical  direction  over  this  section  of  Gondwanaland,  but  at  the 
close  of  the  Permian  a  lengthy  arc  of  compression  (the  Gondwanides) 
came  into  being,  extending  east-west  through  the  south  of  the  Cape, 
the  Sierra  de  la  Ventana,  Sierra  Pintada,  and  northward  to  the 
Puna  de  Atacama,  the  strata  therein  becoming  crumpled  and  in  places 
overturned  to  the  north  and  northeast.  That  these  may  have  been 
“coastal”  ranges  is  suggested  by  the  presence  of  marine  Triassic  and 
Liassic  beds  at  a  few  localities  outside  the  arc,  whereas  just  inside  the 
area  inclosed  by  the  latter — a  ‘  ‘  foreland  ’  ’• — only  continental  deposits 
have  been  found.  During  the  early  Triassic  these  border  ranges 
were,  however,  actively  eroded,  so  that  in  the  later  part  of  that  epoch 
sediments  and  volcanics  were  being  deposited  unconformably  upon 
the  tilted  Devono-Permian  succession,  both  in  the  Cape  and  Argen¬ 
tina,  to  the  south  of  the  fold-belt  in  places  upon  the  pre-Devonian 
basement,  and  to  the  north  and  northeast  thereof  upon  only  slightly 
disturbed  Permian,  and  hence  without  marked  discordance  as  a  rule. 

27  Du  Toit  (1921). 

28  The  conditions  are  more  fully  discussed  by  Du  Toit  (1926),  Chapter  XXI. 


106  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

THE  ARIDITY  OF  THE  CLOSING  TRIASS1C 

The  climate,  which  presumably  had  generally  been  warm  and 
dry,  appears  to  have  finally  become  more  and  more  parched,  until 
toward  the  close  of  the  Triassic  the  material  being  deposited  over 
wide  areas  in  Brazil,  Uruguay,  Paraguay,  and  the  southern  half  of 
the  African  continent  consisted  of  fine-grained,  cream,  pink,  or  red 
sands,  sometimes  with  well-rounded  and  polished  grains  and  with  . 
marked  false-bedding,  stuff  which  must  largely  have  been  of  desert 
origin,  e.g.,  the  Botucatu  and  Rio  de  Rasto  in  the  Parana  Basin,  the 
Forest-Bushveld-Cave  sandstone  of  the  Union,  Southern  and  North¬ 
ern  Rhodesia,  the  Lubilache  of  the  Congo  basin,  and  probably  the 
Adigrat  beds  of  Abyssinia,  covering  areas  totaling  several  millions  of 
square  kilometers. 

Lithologically  these  various  deposits  in  no  small  degree  resemble 
the  Quaternary  Pampean  loess  of  Argentina,  with  its  prevalent  pink¬ 
ish,  sandy  material  with  calcareous  concretions,  largely  windbome 
in  its  origin  and  of  great  thickness  in  places;  in  other  respects  the 
Tertiary- Quaternary  Kalahari  beds  of  Bechuanaland,  with  fluviatile 
and  dune  sands  overlying  in  places  marls,  clays,  and  some  con¬ 
glomerates.  The  fact  that  the  conditions  in  Europe  during  the 
closing  part  of  the  Triassic  were  largely  desert  would  almost  suggest 
a  period  of  universal  desiccation,  although  animal  life  could  by  no 
means  have  been  scanty.  Fluviatile  and  lacustrine  phases  have 
yielded  the  well-known  Thinnfeldia  flora  (together  with  Estheria ), 
significantly  on  the  margins  of  this  gigantic  region,  i.e.,  western 
Argentina,  Chile,  Cape  Province,  peninsular  India,  Tonkin,  New 
South  Wales,  Queensland,  and  Tasmania. 

THE  MESOZOIC  ERUPTIONS 

Outstanding  too,  is  the  enormous  scale  of  the  basic  effusions  at 
the  close  of  the  Triassic,  under  which  vast  territories  in  the  two  con¬ 
tinents  were  flooded  with  basalts,  in  places  to  depths  of  over  1,000 
meters,  i.e.,  the  Parana  basin,  the  limited  region  in  Maranhao,  the 
much-dissected  relics  in  western  Argentina,  together  with  extensive 
outpourings,  mainly  of  acid  character,  in  Neuquen  and  Patagonia, 
the  Stormberg  lavas  of  the  Union  of  South  Africa,  Lebombo,  South¬ 
ern  Rhodesia,  lower  Zambezi  Valley,  and  Kaokoveld.  In  practically 
every  case  thin  sedimentary  intercalations  are  to  be  found  in  the 
basal  part  of  the  volcanic  groups,  certain  of  which  indicate  the  per¬ 
sistence  of  arid  conditions. 

Conspicuous  too  are  the  accompanying  sills  and  dikes  of  dolerite 
(diabase)  that,  avoiding  the  folded  region,  ramify  through  the 
Gondwana  beds  or  penetrate  the  basement  in  the  Karroo  region,  the 
Zambezi  Valley,  Tasmania,  Antarctica,  the  Parana  basin,  and  possi¬ 
bly  Guiana,  and  that  were  injected  during  or  immediately  after  the 
eruptive  phase,  probably  during  the  Liassic. 


GEOLOGICAL  HISTORY  OF  THE  AFRO-AMERICAN  LAND  MASS  107 

THE  JURASSIC  TRANSGRESSION 

The  upward  transfer  of  these  enormous  volumes  of  magma  led 
to  instability  along  the  borders  of  Gondwanaland  and  to  the  trans¬ 
gression  of  the  Liassic  and  Jurassic  ocean  across  its  margins,  and  the 
breaking-up  of  that  continent  seemingly  dates  from  this  period.  We 
find  fossiliferous  marine  beds  with  dolomite  and  gypsum  in  Tunis 
and  Abyssinia,  a  wide  development  of  Jurassic  through  British  East 
Africa,  Tanganyika  Territory,  and  Madagascar,  while  on  the  oppo¬ 
site  side  of  the  land-mass  about  the  border  of  Chile  and  Argentina 
the  Liassic  is  characterized  by  eruptive  matter — rhyolite,  dacite, 
and  spilite — while  marine  beds  of  this  epoch  covering  many  stages 
were  laid  down  along  an  enormous  stretch  of  the  Andine  region. 

THE  CRETACEO-TERTIARY 

It  is  a  striking  fact  that  no  early  marine  Cretaceous  should 
fringe  the  coasts  either  in  the  section  between  Bahia  Blanca  and 
Bahia  or  that  between  Cape  Agulhas  and  Angola,  suggesting,  indeed, 
that  the  two  continents  may  have  still  been  united  at  the  commence¬ 
ment  of  that  epoch,  although  Madagascar  and  India  must  almost 
certainly  have  parted  from  Africa  by  that  time.  The  early  Cre¬ 
taceous  ocean  nevertheless  assuredly  trespassed  over  the  southern 
extremity  of  Africa,  and  also  covered  parts  of  Neuquen  and  the 
Andine  region. 

The  mid-Cretaceous,  so  far  as  can  be  elucidated  the  Turonian, 
saw  a  great  renewal  of  orogenic  movement  in  Africa,  directed  east- 
west  over  the  wide  belt  traversed  by  the  earlier  Cape  foldings,  with 
considerable  marginal  fracturing  both  there  and  in  the  Natal- 
Zululand  coastal  area.  Evidence  of  synchronous  crustal  movements 
has  been  discovered  in  Neuquen,  with  arc-like  flexures  bridging  the 
gap  between  the  Gondwanides  and  the  (posthumous)  Andine  fold¬ 
ings,  while  correlated  flexures  strike  southward  through  Chubut, 
curving  eastward  to  the  mouth  of  the  Rio  Deseado,  disturbances 
that  have  been  called  the  “  Patagonides  ”  by  Windhausen.29  Then 
came  a  period  of  extensive  erosion,  after  which  the  later  Cretaceous 
ocean  transgressed  into  those  regions,  entering  by  an  arm  situated 
between  the  Sierras  of  Buenos  Aires  and  the  Patagonian  platform, 
as  far  inland  as  the  Sierra  Pintada. 

The  weight  of  evidence  would  ascribe  the  base-leveling  in  the 
Sierra  de  la  Vent  ana  and  the  accumulation  of  the  ‘  ‘  high-level  gravels 
to  the  well-established  Eogene  transgression  that  followed  the  first 
phase  of  the  Andine  movements,  while  the  upheaval  thereof  would 
synchronize  with  the  second  phase  and,  preceding  the  “Parana” 
ingression,  date  from  the  early  Pliocene.  The  correspondence  with 
the  southern  Cape  is  hence  remarkably  close. 

28  Windhausen  (1924),  p.  202. 


108  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

A  wealth  of  information  will  be  found  in  the  writings  of  Wind- 
hausen  on  the  palaeogeography  of  northern  Patagonia,  the  outstand¬ 
ing  item  being  the  fact  that  the  Cretaceo-Tertiary  (San  Jorge)  fauna 
of  the  Rio  Negro  and  Chubut  is  of  South  Atlantic  and  Antarctic 
facies  and  does  not  show  North  Atlantic  affinities. 

The  little  that  is  to  be  gleaned  from  Eastern  Brazil  is  confirma¬ 
tory.  The  late  Tertiary  lacustrine  deposits  stand  at  a  relatively  high 
level,  e.g.y  Curitiba,  Sao  Paulo,  and  near  Diamantina,  and  point  to  a 
comparatively  recent  uplift,  while  the  physiography  of  the  Parahyba 
Valley  between  Sao  Paulo  and  Rio  de  Janeiro  strongly  suggests  that 
the  lengthy  crystalline  chain  of  the  Serra  da  Itajuba  running  parallel 
to  the  coast  is  a  fault  scarp  with  downthrow  on  the  ocean  side.  In 
South  Africa,  too,  the  general  movement  of  the  continent  has  been 
in  an  upward  direction  to  the  amount  of  several  hundred  meters. 

THE  ANDINE  MOVEMENTS 

Under  the  displacement  hypothesis  the  South  American  conti¬ 
nent  is  viewed  as  having  proceeded  to  drift  westward  during  the 
latter  part  of  the  Mesozoic,  crumpling  up  in  its  path  the  marine  sedi¬ 
ments  bordering  the  western  side  of  the  Brazilian  “shield,  ”  a  process 
that  led  to  the  extravasation  of  magma  and  the  injection  of  hypabys- 
sal  and  plutonic  matter  into  that  belt  of  extreme  compression  and  of 
upheaval.  The  Tertiary  foldings  and  overthrustings,  directed  usually 
toward  the  east,  that  characterize  the  Cordillera  and  extend  from 
Venezuela  to  Terra  del  Fuego,  find  their  explanation  in  logical  fashion 
under  this  hypothesis,  the  eruptive  matter  being  regarded  not  as  the 
cause  of  such  movements,  but  as  the  product  of  such  compression 
upon  the  zone  underlying  this  belt  of  crumpling,  an  action  that  has, 
moreover,  not  yet  ceased. 

Hindered  by  the  birth  of  these  western  ranges,  the  drainage  of 
the  continent  would  have  been  reversed,  while  the  spasmodic  ele¬ 
vation  of  the  chains  would  have  caused  oscillations  in  the  level  of  the 
slowing  earth-block  and  encroachings  and  retreats  of  the  waters  of 
the  Atlantic.  In  the  broadening  gap  between  Africa  and  South  Amer¬ 
ica  the  presumably  basaltic  ocean-floor  with  its  accumulating  mantle 
of  pelagic  deposits  would  normally  have  been  in  tension,  and  found¬ 
ering  of  sections  thereof  is  a  possibility  that  can  be  invoked  to  explain 
the  volcanicity  of  the  South  Atlantic  basin,  as  exemplified  by  its 
many  volcanic  islands. 

Much  could  be  written  on  the  Tertiary  history  of  this  vast  ocean 
basin  having  an  intimate  and  vital  bearing  on  the  subject  under 
review,  but  enough  has,  I  venture,  been  set  down  to  impress  the 
reader  with  the  exceptionally  illuminating  and  outstanding  character 
of  this  stimulating  theory  of  earth  structure,  undoubtedly  the  most 
fascinating  of  geological  hypotheses  to-day. 


CHAPTER  VII 

BEARING  ON  THE  DISPLACEMENT  HYPOTHESIS 

While  the  general  geological  resemblance  between  those  portions 
of  the  two  continents  that  face  the  South  Atlantic  basin  has  long 
been  perceived,  the  outcome  of  these  present  studies  is  essentially  to 
emphasize  this  geological  parallelism,  which  is  nothing  less  than 
extraordinary,  considering  the  enormous  stretches  of  ocean  parting 
these  two  land-masses. 

Such  points  of  resemblance  have  now  become  so  numerous  as 
collectively  almost  to  exceed  the  bounds  of  coincidence,  while  they 
are,  moreover,  confined  not  to  one  limited  region  nor  to  one  epoch, 
but  implicate  vast  territories  in  the  respective  land-masses  and 
embrace  times  ranging  from  pre-Devonian  almost  to  the  Tertiary. 
Furthermore,  these  so-called  “coincidences”  are  of  a  stratigraphical, 
lithological,  palaeontological,  tectonic,  volcanic,  and  climatic  nature. 

Of  prime  importance ,  moreover ,  is  that  evidence  obtainable  from  the 
study  of  the  phasal  variations  displayed  by  particular  formations  when 
traced  within  their  respective  continents. 

In  illustration,  let  us  consider  the  case  of  two  equivalent  forma¬ 
tions,  the  one  in  South  America  beginning  on  or  near  the  Atlantic 
coast  at  A  and  extending  westward  to  A'  and  the  other  in  Africa 
starting  similarly  near  the  coast  at  B  and  stretching  eastward  to  B'. 
Then  it  can  be  affirmed  that  more  than  one  such  instance  can  be 
designated,  where  the  change  of  facies  in  the  distance  A  A'  or  BB'  is 
greater  than  that  found  in  AB,  although  the  full  width  of  the  Atlantic 
intervenes  between  A  and  B.  In  other  words,  these  particular  forma¬ 
tions  along  the  two  opposed  shores  tend  to  resemble  one  another 
more  closely  than  either  one  or  both  of  their  actual  and  visible 
extensions  within  the  respective  continents.  With  the  multiplication 
of  such  examples,  drawn  from  more  than  one  geological  epoch,  such 
a  singular  relationship  can  no  longer  be  regarded  as  wholly  fortuitous 
and  a  definite  explanation  therefore  has  accordingly  to  be  sought. 
An  analysis,  moreover,  shows  that  this  unexpected  tendency  is 
equally  marked,  whether  the  formations  involved  be  marine,  deltaic, 
continental,  glacial,  eolian,  or  volcanic. 

If,  on  the  other  hand,  the  two  land-masses  are  pictured  as  having 
been  moved  closer  together,  as  in  Figure  7,  a  great  number  of  obser¬ 
vations  and  deductions  are  now  found  to  be  brought  into  apparent 
harmony,  and  these  possible  “coincidences”  are  disposed  of  in  the 
simplest  fashion. 

This  is  precisely  what  the  displacement  hypothesis  effects,  there¬ 
by  providing  a  simple  explanation  of  many  otherwise  puzzling 

109 


110  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

observations.  The  fact  that  many  eminent  scientists  have  cast  doubt 
upon  its  geophysical  possibility  should  not  be  permitted  to  cloud  the 
issue  any  more  than  that  the  existence  of  former  “land  bridges’' 
should  be  denied  because  of  cogent  objections  based  upon  the  doc¬ 
trine  of  isostasy. 

It  is  not  proposed  to  discuss  here  the  physical  basis  of  that 
hypothesis,  nor  is  it  desired  to  deal  with  this  problem  as  a  whole, 
such  as  has  been  done  by  Wegener.30  The  intention  is  merely  to  set 
forth  some  of  the  data  regarding  Africa  and  South  America  and  to 
state  the  conclusions  to  be  drawn  therefrom,  that  are  distinctly 
awkward  of  explanation  under  the  current  and  orthodox  view  of 
“land  bridges,”  but  which,  on  the  contrary,  appreciably  favor  the 
“hypothesis  of  continental  disruption.”  Incidentally,  some  few 
observations  will  be  made  having  a  bearing  upon  other  parts  of 
Gondwanaland,  that  in  turn  suggest  lines  of  future  research  in  those 
particular  countries. 

Of  prime  importance  is  the  extraordinarily  close  correspondence 
in  the  outlines  of  the  opposed  shores  of  the  two  continents,  as  has 
been  pointed  out  and  discussed  by  others  long  before  Wegener,  and 
which  is  particularly  marked  when  comparison  is  made  not  with 
maps,  but  on  the  face  of  a  terrestrial  globe.  Next  is  the  presence  of  the 
central  Atlantic  rise  beneath  the  ocean,  with  its  surprisingly  sym¬ 
metrical  position  nearly  midway  between  the  Old  World  and  the  New. 

Interpreted  mathematically ,  the  great  regularity  of  these  three 
features,  extending  through  the  entire  length  of  the  South  Atlantic, 
would  betoken  an  enormously  high  probability  that  such  features  had 
owed  their  origin  to  one  and  the  same  set  of  tectonic  forces  at  a 
relatively  late  geological  period.  Upon  this  rise  are,  furthermore, 
aligned  certain  of  the  volcanic  islands  of  the  southern  Atlantic.  This 
otherwise  profitable  subject  must,  however,  be  relinquished  in  favor 
of  the  more  momentous  geological  aspect. 

Commencing  in  the  south,  the  following  relationships  can  be 
considered  as  more  or  less  established : 

*  (I)  The  section  south  of  Bahia  Blanca  and  that  below  the  Zuurberg 

in  the  Uitenhage  district  show  several  points  of  agreement  in  that : 
(a)  The  upper  Triassic  (i)  is  predominantly  of  volcanic  origin,  (2) 
rests  discordantly  upon  Permian  or  older  beds  that  are  affected  by 
Permo-Triassic  movements,  (3)  is  influenced  by  mid-Cretaceous 
disturbances  following  more  or  less  the  older  tectonic  axes,  and  (4) 
is  overlain  by  marine  Cretaceous  and  Tertiary,  the  former  of  which 
contains  variegated  clays  and  is  in  places  gypsiferous.  In  the  Cape 
the  volcanics  are,  however,  basic,  in  Argentina  largely  acid,  though 
in  Mendoza  and  San  Juan  basaltic  flows  are  represented.  ( b )  The 
lower  Cretaceous  in  northwestern  Neuquen  on  the  southern  side  of 

30  Wegener  (1924). 


BEARING  ON  THE  DISPLACEMENT  HYPOTHESIS 


111 


the  “  Gondwanides  ”  contains  a  typical  “Uitenhage”  invertebrate 
fauna,  this  being  the  only  part  of  South  America  where  such  a 
faunal  assemblage  has  yet  been  found,  and  like  that  in  the  Sundays 
River  Valley  has  been  tilted  before  late  Cretaceous  times.  ( c )  There 
are  great  developments  of  nearly  flat  marine  Tertiaries  from  Eocene 
to  Pliocene  in  age,  in  which  most  strikingly  an  “Atlantic”  fauna  is 
not  at  all  or  only  partially  represented. 

(II)  The  ranges  north  of  Bahia  Blanca  undoubtedly  correspond 
with  the  Cape  Fold  ranges,  in  each  case  showing:  (a)  Intense  fold¬ 
ing,  with  overturning  toward  the  north  or  northeast,  strata  up  to  the 
Permian  being  involved.  ( b )  The  quartzites  of  the  Sierra  de  la  Ven- 
tana  correspond  lithologically  with  the  Table  Mountain  sandstone 
of  the  region  about  Mossel  Bay  and  George,  (c)  The  fossiliferous 
Devonian  is  like  that  of  the  latter  region,  but  the  equivalent  of  the 
Witteberg  series  is  composed  of  greywackes  instead  of  hard  white 
quartzites.  ( d )  The  thick,  folded  and  cleaved  glacials  in  Argentina 
duplicate  the  characters  of  the  Dwyka  tillite  and  are  conformable 
with  the  beds  below,  as  in  the  Cape  south  of  latitude  33 °  S.  (e)  In 
Argentina,  dark  shales  overlie  the  glacials,  as  in  the  Cape,  and  pass 
up  into  beds  like  the  Ecca  of  the  southwestern  Karroo,  only  some¬ 
what  more  quartzitic,  but  in  the  first-named,  just  as  in  Pondoland, 
the  horizon  with  Mesosaurus  is  not  recognizable.  (/)  Dolerite  intru¬ 
sions  are  absent  in  each  case,  (g)  Consolidated  ferruginous  “gravels” 
rest  on  bevels  cut  across  the  folded  beds  on  the  northern  flanks  of  the 
Sierra  de  la  Vent  ana  and  duplicate  in  most  extraordinary  fashion 
the  early  Tertiary  “high-level  gravels”  of  the  south  of  the  Cape, 
having  similarly  been  raised  and  dissected  at  a  subsequent  date. 

( h )  Traced  northwestward  from  Sierra  de  la  Vent  ana  into  San  Juan 
and  Jachal,  the  lower  Devonian  quartzites  have  become  darker  and 
less  like  the  Table  Mountain  sandstone,  the  fossiliferous  slates 
greener,  the  equivalent  of  the  Witteberg  is  apparently  represented  by 
grits  and  greywackes,  the  glacials  now  rest  unconformably  on  the 
older  divisions  and  show  characters  very  different  from  those  in 
the  Cape,  at  the  same  time  becoming  compound;  tfie  plants 
include  northern  Carboniferous  forms,  while  the  succeeding  strata, 
the  equivalent  of  the  Ecca,  become  quite  unlike  those  of  the  west¬ 
ern  Cape. 

(III)  To  the  northeast  of  the  Sierra  de  la  Ventana  the  “Gond- 
wanides”  are  fading  out,  and  at  Olavarria  and  Tandil  the  pre- 
Devonian  rocks  are  only  slightly  affected  by  them,  though  a  folding 
transverse  thereto,  trending  northeastward,  can  be  made  out,  thus 
paralleling  the  conditions  between  Clan  william  and  Namaqualand. 
Closer  comparison  is  impossible,  since  the  Pampean  of  the  lower 
ground  round  about  conceals  these  older  groups. 

(IV)  Comparing  the  region  stretching  from  Uruguay  to  Minas 


112  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

in  Brazil  with  that  between  Clan  william  and  the  Kaokoveld,  we  find : 
(a)  The  almost  horizontal  Furnas  sandstone  of  Parana  is  similar  to 
the  equivalent  Table  Mountain  sandstone  of  Clan  william  and  Van 
Rhynsdorp.  (b)  Each  is  thinner  and  softer  than  in  the  south  and  each 
carries  small  quartz  pebbles,  (c)  Each  is  succeeded  by  the  marine 
Devonian  shales  with  calcareous  nodules — Ponta  Grossa  shales  and 
Bokkeveld  beds — with  closely  allied  austral  faunas,  (d)  The  soft 
Tibagy  sandstone  with  Spirifers  duplicates  the  “  Fossiliferous  sand¬ 
stone”  of  the  Bokkeveld  of  Ceres  and  Clan  william,  (e)  The  base  of  the 
Itarare  glacials  is  unconformable  and  transgressive,  exactly  as  is  the 
case  with  the  Dwyka  in  Calvinia,  which  stratigraphical  relation  is 
maintained  toward  the  north.  (/)  There  is  irregularity  in  the  charac¬ 
ter  and  thickness  of  the  glacials  in  each  country,  owing  to  the 
uneven  nature  of  the  floor,  etc.  (g)  The  glacials  are  absent  at  the 
base  of  the  Gondwana  system  in  Rio  Grande  do  Sul  and  in  Santa 
Catherina,  just  as  in  parts  of  the  Transvaal.  Qi)  A  southeasterly 
source  is  presumed  for  the  Brazilian  glacials,  a  northerly,  north¬ 
easterly,  and  perhaps  northwesterly  origin  for  those  in  the  western 
Cape  and  in  Southwest  Africa,  (i)  The  Iraty  shales  are  identical 
lithologically  and  palaeontologically  with  the  White  band  of  the 
Dwyka,  each  containing  the  reptile  Mesosaurus,  not  known  in  other 
parts  of  the  world.  The  South  African  formation  is  fully  developed 
from  Robertson  across  to  Grahamstown  and  northward  to  Mariental, 
but  is  not  represented  in  Natal,  the  Transvaal  or  about  Palapye;  the 
South  American  extends  from  Uruguay  to  Sao  Paulo  and  westward 
into  Paraguay,  but  is  unknown  in  the  bore-holes  in  Argentina  west 
of  the  Parana  River  or  in  Bolivia.  Thus  the  basin  within  which  this 
uncommon  type  of  originally  organic  sulphureted  mud  was  deposited 
is  fairly  well  defined  and  must  have  formed  an  estuary  opening 
probably  to  the  north,  where  the  facies  becomes  calcareous,  a  con¬ 
clusion  to  which  the  presence  of  a  marine  phase  in  the  glacials  in 
Parana  and  Southwest  Africa  would  give  support,  (j)  An  important 
difference  is  to  be  found  through  the  Brazilian  Bonito  or  “coal 
measures  ”  underlying  this  horizon,  whereas  the  Natal  and  Transvaal 
Ecca  “coal  measures”  succeed  the  latter,  but  I  should  like  to  record 
that  in  the  western  Karroo  I  have  found  a  zone  of  gray  fissile 
sandstones  such  as  is  unrepresented  farther  to  the  east  or  northeast, 
in  corresponding  position  in  the  upper  Dwyka  shales.  Presumably 
the  Bonito  is  a  deltaic  phase  that  “invaded”  the  basin  in  which 
the  “post-glacial”  deep-water  shales  were  being  laid  down,  (k)  The 
Estrada  Nova,  which  shows  resemblance  to  stages  II  and  III  of  the 
Paganzo,  but  not  to  the  presumably  equivalent  horizon  of  Bolivia, 
strongly  recalls  the  Ecca  of  southwest  Africa,  which  again  is  widely 
different  from  that  of  the  Cape,  Transvaal,  and  Rhodesia.  Silicified 
wood  is  common  in  both  countries,  but  marine  mollusca  of  this  age 


BEARING  ON  THE  DISPLACEMENT  HYPOTHESIS 


113 


have  not  yet  been  found  in  South  Africa.  (/)  The  higher  Permian 
beds  are  apparently  absent  from  the  Parana  basin  and  from  South¬ 
west  Africa,  which  has  seemingly  been  the  result  of  the  positive 
earth  movements  at  the  close  of  the  Palaeozoic,  (m)  The  Sao  Bento 
series  is  pseudo-conformable  to  the  underlying  strata  in  the  Parana 
basin,  just  as  the  Stormberg  series  rests  without  angular  break  upon 
the  upper  Beaufort  series  in  the  north  of  the  Orange  Free  State  or 
upon  the  Ecca  in  the  central  Transvaal,  (i)  Each  series  transgresses 
across  the  lower  Gondwanas,  i.e.,  along  the  margins  of  the  Parana 
basin  and  in  the  region  lying  to  the  north  and  northeast  of  the  Cape 
Province;  (2)  strata  with  the  “ Thinnfeldia  flora”  are  developed 
toward  the  base,  almost  solely  in  the  south,  i.e.,  in  the  Cape-Basuto- 
land  region  and  in  western  Argentina  and  the  fresh- water  crustacean 
Cyzicus  (. Estheria )  draperi  is  common  to  both  these  areas;  (3)  the 
brilliantly  colored  Rio  do  Rasto  parallels  the  Stormberg  Red  beds  and 
Bushveld  marls  and  like  the  latter  formations  contains  dinosaurian 
remains  belonging  to  allied  forms ;  (4)  the  Botucatu  and  uppermost 
portion  of  the  Rio  do  Rasto  agree  lithologically  with  the  Cave- 
Bushveld-Forest  sandstone,  all  of  which  have  been  formed  largely 
by  eolian  agency  under  an  arid  climate;  silicification  of  the  sand¬ 
stones  is  common;  (5)  the  succeeding  and  widespread  volcanics  are 
interbedded  in  their  basal  portions  with  thin  sandstone  bands  or 
tufaceous  sandstones;  (6)  the  only  places  where  the  volcanics  form 
the  actual  coast  are  near  Torres  and  in  the  Kaokoveld  respectively  ; 
(7)  the  lavas  are  basalts  with  but  little  olivine  or  else  basaltic  andes¬ 
ites,  but,  while  ophitic  and  subophitic  structures  are  the  rule  in  the 
Cape,  a  porphyritic  structure  is  occasional  in  southern  Rhodesia  and 
is  dominant  both  in  the  Kaokoveld  and  in  the  Parana  basin,  while 
tuffs  are  rare.  They  show  bands  of  pipe-amygdaloid  and  were  evi¬ 
dently  poured  out  in  rapid  succession,  apparently  under  a  dry  climate 
and  presumably  from  fissures,  for  except  in  the  Basutoland  region 
volcanoes  are  practically  unknown ;  (8)  these  effusions  terminate  the 
succession  in  both  countries,  (m)  Widespread  injections  of  dolerite 
characterize  the  flat -lying  Karroo  of  the  Cape,  Natal,  and  southwest 
Africa  and  also  the  Parana  basin,  but  are  not  found  in  the  south  of 
the  Cape,  northern  Transvaal,  or  Southern  Rhodesia  generally,  nor  in 
southern  or  western  Argentina.  ( n )  Marine  Jurassic  and  Cretaceous 
beds  are  absent  from  along  the  opposite  coasts.  (0)  Kimberlite  and 
melilite-basalt  of  presumably  late  Cretaceous  age  pierce  the  strata 
in  the  form  of  pipes  both  in  South  Africa  (for  example,  in  Namaqua- 
land  and  the  Gibeon  district)  and  in  eastern  Brazil  (for  example,  in 
the  Serra  das  Lages  100  km.  from  Rio  de  Janeiro,31  and  at  Patos,  in 
the  western  half  of  Minas,  where  a  neck  penetrates  Triassic  sand¬ 
stone).  (p)  The  Cretaceous  of  east-central  Brazil  is  largely  a  conti- 

31Rimann  (1915). 


114  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

nental  deposit  covering  a  huge  region  in  the  interior,  overlapping  the 
Sao  Bento  volcanics  and  paralleling  in  certain  ways  the  extensive 
Kalahari  beds  of  southwest  Africa,  (q)  The  detrital  diamonds  of  south¬ 
west  Africa  that  have  been  derived  from  Tertiary  marine  beds  near 
Luderitz  are  quite  unlike  those  won  from  the  kimberlite  pipes  of 
South  Africa,  but  show  crystallographic  and  physical  points  of 
resemblance  with  the  gems  obtained  in  eastern  Brazil  from  gravels 
or  from  pipes,  such  as  the  Boa  Vista  Mine,  piercing  the  Espinago 
quartzites  and  apparently  of  pre-Gondwana  age.  (r)  The  pre-Devo¬ 
nian  beds  consist  of  quartzites,  limestones,  and  slates  folded  along 
axes  roughly  parallel  to  the  respective  coasts  and  injected  in  places 
by  granitic  bodies,  i.e.,  the  Bambuhy  and  Assunguy  series,  at  inter¬ 
vals  from  Bahia  to  Uruguay,  and  the  Nama  system  from  Luderitz 
to  Cape  Agulhas.  (5)  Brouwer  has  called  attention  to  the  presence 
of  several  centers  of  alkaline  rocks,  both  plutonic  and  effusive,  on 
either  side  of  the  Atlantic,  for  example,  in  Southwest  Africa  the 
important  group  of  foyaites  of  the  Granit  Berg,  etc.,  and  the  phono- 
lites  of  the  Klinghardt  Mountains  near  Luderitz,  and  in  Brazil  the 
well-known  Poqos  de  Caldas  north  of  Sao  Paulo,  the  various  similar 
occurrences  in  the  State  of  Rio  de  Janeiro,  such  as  the  Serra  de 
Gericino,  Serra  de  Tingua,  Cabo  Frio,  etc. 

(V)  Proceeding  farther  north  we  find:  (a)  Opposed  to  the  dis¬ 
turbed  area  of  Cretaceous  and  Tertiary  of  Angola  and  Loanda  are 
those  of  Bahia  and  Sergipe,  in  which  their  equivalents,  with  similar 
faunal  elements  of  the  Atlantic  and  Mediterranean  types,  display 
somewhat  less  tilting,  (b)  Inland  therefrom  in  Brazil  are  the  folded 
Permian  and  probably  Carboniferous  Estancia  beds,  with  some 
resemblances  to  the  Kundulungu  of  the  lower  Congo  region,  while 
beneath  the  latter  lies  a  great  calcareo-dolomitic  formation,  which 
may  perhaps  be  compared  with  the  ancient  limestones  of  Bahia. 

(VI)  Farther  north  is  found  a  belt  of  Cretaceo-Eocene  along  the 
coast  from  Natal  westward  that  rises  up  to  form  the  plateau  along 
the  boundary  of  Ceara  with  Piauhy  and  is  seen  again  in  the  northern 
part  of  Maranhao.  These  strata  can  be  compared  with  the  beds  of 
approximately  similar  age  in  the  coastal  portions  of  Gold  Coast, 
Dahomey,  and  Cameroons,  extending  up  the  valleys  of  the  Niger  and 
Benue  and  occupying  a  wide  area  to  the  north.  In  Nigeria  the 
Cretaceous  is  somewhat  folded  and  faulted.  Reference  might  be 
made  to  the  well-known  volcanic  line  of  the  Cameroons  that  extends 
southwest  ward  into  the  ocean,  in  view  of  the  presence  off  the  comer 
of  Brazil  of  the  phonolite  island  of  Fernando  Noronha. 

(VII)  The  Gondwana  outlier  of  Maranhao  and  Piauhy  consti¬ 
tutes  a  fairly  close  parallel  with  the  development  known  as  the  Lubi- 
lache  in  the  western  part  of  the  Congo  Basin  in  ( a )  the  absence  of  the 
glacial  group,  (b)  the  absence  of  coals,  (c)  the  equivalence  apparently 


BEARING  ON  THE  DISPLACEMENT  HYPOTHESIS 


115 


of  the  upper  red  sandstones  of  Brazil  with  the  cream  and  red  friable 
sandstones  in  the  Congo.  Mesozoic  volcanics  are,  however,  not  yet 
known  in  west-central  Africa,  whereas  the  Brazilian  strata  are  over- 
lain  by  basalts  and  penetrated  by  dolerites. 

(VIII)  The  Silurian  and  Devonian  strike  south-south  west  ward 
through  the  Sahara  and  southwestward  through  West  Africa,  with 
isolated  patches  of  the  latter  system  in  Gold  Coast  Colony,  and  are 
apparently  not  much  disturbed  generally,  a  condition  that  can  be 
paralleled  with  the  corresponding  systems  forming  the  syncline  of 
the  lower  Amazon  Valley  resting  on  the  Archaean  granite,  with  trend 
oblique  to  the  coast -line,  the  more  so  in  that  the  Devonian  in  each 
case  includes,  in  addition  to  European  elements,  some  North  Ameri¬ 
can  forms,  and  also  displays  certain  important  affinities  with  the 
austral  fauna.  Presumably  land  lay  to  the  south,  and  along  that 
Devonian  coast  migration  was  possible  toward  Europe  in  the  one 
direction  and  toward  Amazonas,  Matto  Grosso,  and  Bolivia  in  the 
other.  A  point  that  might  be  noted  in  view  of  the  diamondiferous 
deposits  of  the  Guianas  is  the  frequency  with  which  that  gem  occurs 
in  the  coastal  belt  of  West  Africa,  e.g.,  in  Liberia  and  Gold  Coast. 

While  the  above  can  be  taken  as  merely  summarizing  the  evidence 
on  the  subject,  it  will  be  clear  to  all  acquainted  with  the  literature 
that  many  other  points  of  similarity  or  else  of  analogy  could  readily 
be  discovered  in  the  geology  of  these  two  land-masses.  Sufficient,  I 
venture  to  think,  has  already  been  set  down  to  bring  out  the  aston¬ 
ishing  geological  agreement  between  more  or  less  comparable  sections 
of  the  respective  coastal  zones,  from  which  it  will  be  conceded  that 
the  evidence  so  far  would  distinctly  appear  to  favor  the  displacement 
hypothesis  rather  than  orthodox  ideas.  It  is  nevertheless  highly 
desirable  that  more  impartially  minded  persons  should  criticize  the 
data  here  given  and  judge  whether  those  amazing  resemblances  have 
been  correctly  interpreted  or  whether  some  more  rational  explana¬ 
tion  for  them  could  not  be  formulated. 

Accepting  provisionally  this  hypothesis ,  it  will  next  be  instructive 
to  attempt  some  graphic  representation  thereof. 

Regarding  the  various  possible  dispositions  of  the  continental 
masses,  it  can  first  of  all  be  remarked  that  actual  contiguity  of  the 
opposed  shore-lines  can  most  definitely  be  ruled  out,  and,  secondly, 
that  even  apposition  of  the  borders  of  the  continental  shelves,  as 
favored  by  Wegener,  may  perhaps  hardly  be  warranted,  for  utilizing 
the  line  of  reasoning  based  on  phasal  variation ,  the  differences  actu¬ 
ally  noticed  between  the  various  facies  of  the  equivalent  formations 
where  they  come  closest  together  are  of  such  a  degree  as  to  demand 
a  fairly  wide  gap.  One  of  the  order ,  perhaps  of  from  400  to  800  km., 
would  indeed  seem  to  he  needed ,  if  all  the  observed  phenomena  are  to 
he  satisfactorily  accounted  for. 


116 


GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 


-  Cretaceous  and 
l  Eocene 

✓ 

.  Condwana 

«*— • — 


Silurian ,  Devonian' 
and  Carboniferous 

Late  Eozoic  and 
e  a  r/y  Pa  la  e  oz  oic  ■ 

•  Gondwanides  and 
Cape  fold  in  3s 


v 

v  V 


V  V 


Granitic  basement 


PosPTriassic  uplifts 

Fig.  7 — Suggested  continental  restoration  under  the  Displacement  Hypothesis. 


- Limit  of  Mesosaurus 

— . -  And  me  fold  mss 

- BrasiUdes  and 

Post-Nama  foldings 


BEARING  ON  THE  DISPLACEMENT  HYPOTHESIS 


117 


Such  is  schematically  represented  in  Figure  7,  which  is  tentatively 
suggested  as  perhaps  best  meeting  the  needs  of  the  case,  though  the 
intervening  space  is  actually  a  little  less  than  the  phasal  variations 
would  rightly  demand. 

Further  critical  comparative  studies  should  enable  a  better  ori¬ 
entation  to  be  made,  the  diagram  advanced  being  admittedly  only 
a  first  approximation.  Granted,  too,  that  such  crustal  slipping  could 
have  taken  place,  it  must  not  be  overlooked  that  some  regional  dis¬ 
tortion  might  have  resulted  during  the  drifting  apart  of  the  floating 
continental  blocks,  an  action  inferred  from  the  inflection  of  the 
Andine  foldings  in  the  neighborhood  of  Cape  Horn. 

It  will  be  noticed  that  in  this  figure  the  Falkland  Islands  have, 
following  the  discussion  in  Chapter  VI,  been  moved  up  into  a  posi¬ 
tion  between  Cape  Town  and  La  Plata.  Only  now  can  the  remark¬ 
able  correspondence  of  the  various  fold-lines,  and  even  of  the  more 
moderate  archings,  of  different  ages  be  properly  appreciated.  The 
rupture  of  the  Afro-American  mass  is  also  more  than  hinted  at  in  the 
strict  parallelism  of  the  zigzagging  of  the  two  coast-lines  near  Rio 
de  Janeiro  and  Angola  respectively.  It  is  surprising,  too,  though  not 
deliberately  arranged,  that  the  space  between  the  two  shores  should 
correspond  so  closely  in  its  two  boundaries  with  the  plan  of  the 
“central  ridge”  of  the  South  Atlantic.  These  two  sections  of  coast¬ 
line,  it  should  furthermore  be  noted,  are  composed  of  crystalline 
rocks,  whereas  both  to  the  north  and  south  considerable  stretches 
can  be  found  where  late  Tertiary  and  Quaternary  marine  sediments 
fringe  the  shores  and  consequently  tend  to  obscure  the  original  out¬ 
lines  of  the  supposedly  fractured  masses. 

Further  elaboration  is  hardly  necessary,  and  the  diagram  is 
accordingly  left  to  the  criticism  of  the  reader. 


CHAPTER  VIII 

CONCLUSIONS 

Throughout  this  work  the  intention  has  been  to  detail  the  geo¬ 
logical  peculiarities  of  the  opposed  sections  of  the  two  land-masses, 
to  point  out  their  resemblances  and  differences,  and  to  draw  such 
legitimate  conclusions  in  regard  to  the  geographical,  climatic,  and 
other  circumstances  in  each  country  as  the  facts  would  appear  to  the 
writer  to  warrant,  though  irrespective  of  any  particular  theory  of 
continental  union  during  the  past,  for  that  they  were  so  united  is 
indicated  by  a  wealth  of  evidence  of  a  practically  indisputable 
character. 

But,  having  proceeded  thus  far,  one  could  scarcely  avoid  making 
use  of  these  data  and  indulging  in  a  certain  amount  of  speculation  as 
to  their  possible  manner  of  union  during  the  later  Palaeozoic  and 
early  Mesozoic  eras.  Such  an  analysis,  it  can  be  affirmed,  does  not 
favor  the  notion  of  one  or  more  relatively  narrow  connecting  links  or 
“land  bridges”  lasting  down  into  the  early  Mesozoic,  but  on  the 
contrary  supports  the  presumption  of  some  continuous  land  area 
embodying  those  sections  of  Gondwanaland  that  are  now  represented 
in  the  two  continents.  It  furthermore  strongly  favors  the  admittedly 
revolutionary  idea  that  geographically  these  two  portions  were 
appreciably  closer  in  the  past;  indeed,  the  evidence  is,  I  think,  of 
sufficient  weight  to  warrant  such  a  viewpoint  being  adopted,  as  a 
working  hypothesis  at  any  rate.  Upon  studying  the  remnants  of 
Gondwanaland  in  the  other  continents — India,  Australia,  etc. — we 
find  the  facts  and  the  deductions  therefrom  in  similar  accord,  and 
the  impression  becomes  decidedly  strengthened  that  the  displace¬ 
ment  hypothesis,  if  not  an  actual  explanation  of  the  phenomena, 
would  at  least  seem  to  contain  more  than  a  germ  of  the  truth, 
despite  its  revolutionary  and  heterodox  nature  and  apparent  lack 
of  agreement  with  geophysical  considerations. 

Nevertheless,  as  already  remarked,  geological  evidence  almost 
entirely  must  decide  the  probability  of  this  hypothesis,  for  those 
arguments  based  upon  zoo-distribution  are  incompetent  to  do  so, 
being  as  a  rule  equally,  though  more  clumsily,  explicable  under  the 
orthodox  views  involving  lengthy  land  connections  afterward  sub¬ 
merged  by  the  oceans. 

The  hypothesis  sets  forth  to  explain  in  simple  and  logical  fashion 
a  host  of  problems — geological,  palaeontological,  tectonic,  climatic, 
and  biological — that  have  hitherto  proved  difficult  or  impossible  of 
satisfactory  solution,  and  is  incidentally  serving  to  stimulate  geo- 

118 


CONCLUSIONS 


119 


logical  thought  in  fashion  almost  unparalleled  in  the  history  of 
that  science.  For  example: 

(1)  It  condenses  all  the  sections  of  Gondwanaland  with  their 
markedly  similar  formations  and  geological  histories  within  the 
compass  of  one  moderately  sized  continent ,  instead  of  demanding  a 
land-mass  very  much  larger  than  Eurasia. 

(2)  It  brings  into  close  association  away  from  the  equator  all  the 
areas  glaciated  in  the  “Permo-Carboniferous”  and  thus  succeeds  in 
eliminating  an  outstanding  difficulty  in  necessitating  somewhere  or 
other  a  refrigeration  in  the  subtropics  or  tropics,  a  trouble  inherent 
under  any  other  hypothesis,  even  in  those  postulating  a  wide  move¬ 
ment  of  the  South  Pole. 

(3)  It  can  explain  the  apparent  non- synchronism  of  glaciation  in 
the  several  sections  and  many  other  observed  peculiarities  as  pri¬ 
marily  due  to  the  progressive  migration  of  the  main  ice  center  or 
centers. 

(4)  It  simplifies  the  problem  of  the  distribution  of  the  ‘  ‘  Glossop- 
teris  ”  and  “  Thinnfeldia  ”  floras. 

(5)  It  brings  together  the  wide  areas  over  which  arid  conditions 
seem  generally  to  have  prevailed  at  the  close  of  the  Triassic.  In 
making  a  review  of  this  problem  nothing  is  more  conspicuous  than 
the  tendency  under  the  orthodox  viewpoint  of  overlooking  the  enor¬ 
mous  improbability  that  over  widely  separated  parts  of  the  globe, 
situated  in  different  latitudes  and  longitudes  and  under  totally 
differing  oceanic  environments  (and  therefore  of  atmospheric  dis¬ 
tributions)  there  should  have  coexisted  huge  areas  throughout  the 
entirety  of  which  the  climate  should  consistently  have  at  any  one 
epoch  been  either  frigid  or  pluvial  or  arid. 

(6)  It  assembles  the  earlier  Mesozoic  lava-fields. 

(7)  It  would  explain  Gondwanaland  as  a  well-defined  and  almost 
isolated  unit  down  to  about  the  end  of  the  Jurassic  epoch,  after  which 
the  continental  mass  is  viewed  as  proceeding  to  break  up  and  the 
sectors  to  begin  drifting  apart,  with  the  Cretaceous  ocean  progres¬ 
sively  penetrating  between  the  blocks  and  generally  coming  to  over¬ 
lap  their  borders  in  the  fully  established  marine  transgressions  of 
the  late  Mesozoic. 

In  the  hypothesis  as  formulated  by  Wegener,  the  New  World  is 
regarded  as  having  parted  from  the  Old  up  the  full  length  of  the 
Atlantic  from  south  to  north  at  quite  a  late  stage  in  the  Tertiary,  * 
against  which  supposition  many  objections  could  be  raised.  Else¬ 
where32  I  have  tentatively  suggested  the  radically  different  concep¬ 
tion  of  two  such  parent  continents,  that  to  the  south  being  Gond¬ 
wanaland,  which,  by  impinging  on  each  other,  gave  rise  to  the  enor¬ 
mously  extended  orogenic  structures  made  by  the  Atlas,  Alps, 

32  Du  Toit  (1921a). 


120  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

Carpathians,  Caucasus,  Himalayas,  etc.,  or,  as  Suess  has  called 
them,  the  “Posthumous  Altaides.  ”  Concentrating  attention  upon 
the  southern  continent,  it  can  be  pointed  out  that  one  of  the  deter¬ 
mining  factors  in  the  conjectured  breaking  up  of  the  mass  may  have 
been  the  development  around  the  continental  “shield”  of  the 
peripheral  trough  of  subsidence  or  “fossa,  ”  within  which  sedimenta¬ 
tion  had  proceeded  through  lengthy  periods  during  Palaeozoic,  Meso¬ 
zoic,  and  even  Cainozoic  times,  whereby  an  engirdling  zone  of  crustal 
weakness  would  have  been  produced  favoring  the  centrifugal  separa¬ 
tion  postulated. 

These  encircling  oceanic  deposits  would  thereafter  have  been 
pushed  up  into  folds  in  advance  of  the  drifting  crustal  sectors,  a 
process  that  would  ultimately  have  served  to  arrest  their  outward 
movement,  for,  in  conspicuous  fashion,  excluding  “Angaraland,  ”  all 
the  known  portions  of  Gondwanaland  now  lie  within  a  practically 
closed  orogenic  ring  constituted  by  the  Atlas,  south  European, 
Iranian,  and  Himalayan  folds  on  the  north,  the  Malay,  Polynesia, 
and  New  Zealand  crumplings  on  the  east,  the  west  Antarctica  belt 
on  the  soutlp  and  the  Andine  flexures  on  the  west,  curving  eastward 
into  Venezuela.  Along  certain  sections  of  this  “orogen,  ”  to  use 
Kober’s  term,  intense  compression  and  overthrusting  then  took 
place,  accompanied  by  considerable  magmatic  activity. 

Such  a  view  would,  moreover,  serve  to  explain  the  temporary 
reunion  of  certain  of  the  continents  at  some  stage  in  the  Tertiary,  as 
the  facts  of  zoographical  distribution  would  apparently  demand.  A 
rather  similar  process  is  conceived  to  have  operated  in  the  Northern 
Hemisphere,  where  the  continental  fragments  lie  within  a  great  oval 
ring  of  mainly  Tertiary  foldings,  from  Mexico  to  Alaska,  Japan,  the 
Himalayas,  and  onward  as  before.  These  two  orogenic  belts  are 
pressed  together  in  the  section  extending  from  the  West  Indies  to 
the  East  Indies,  in  which  two  regions  distorted  arcs  with  marked 
inflections  have  originated  from  their  supposed  mutual  interference. 
As  will  be  observed  from  a  map,  these  two  orogenic  “fossae,  ”  when 
rolled  out  into  one  plane,  come  to  resemble  a  figure  8,  while  the 
remainder  of  the  surface  of  the  globe  constitutes  the  immense 
basin  of  the  Pacific,  along  the  margins  of  which  the  two  fold-systems 
have  crowded. 

SOME  GENERAL  REMARKS 

These  pages  have  of  necessity  dealt  in  very  summary  fashion 
with  this  fascinating  subject,  more  particularly  as  related  to  those 
territories  beyond  the  respective  opposed  regions  known  personally 
to  the  writer.  It  is  therefore  to  be  hoped  that  scientists  acquainted 
with  those  particular  outside  regions  may  be  induced  to  set  down 
their  observations  on  those  areas,  supporting  or  else  refuting  the  pre- 


! 


BIBLIOGRAPHY 


121 


sumptions  here  put  forward  on  behalf  of  this  hypothesis,  since  a 
strict  and  impartial  criticism  is  indeed  required  if  this  riddle  in  early 
history  is  to  be  deciphered.  The  cooperation  of  geologists,  palaeon¬ 
tologists,  zoologists,  botanists,  and  physicists  is  urgently  needed,  the 
discussion  advanced  here  dealing  admittedly  with  only  a  very 
limited,  albeit  extremely  important,  section  of  the  globe,  from  which, 
under  the  eclectic  hypothesis  of  crustal  instability,  corroborative  or 
destructive  evidence  might  reasonably  be  expected.  By  virtue  of 
their  enormous  lengths  of  opposed  coast-line  and  extraordinary  geo¬ 
logical  parallelisms,  the  two  most  favored  continents  from  which  evi¬ 
dence  is  to  be  drawn  would  appear  to  be  Africa  and  South  America, 
and,  should  the  details  herein  set  forth  appear  to  be  worthy  of 
serious  consideration,  it  is  to  be  hoped  that  more  detailed  investiga¬ 
tions  may  shortly  be  instituted  elsewhere  on  the  two  sides  of  the 
Atlantic  for  the  purpose  of  clearing  up  some  of  the  many  crucial 
questions  that  must  be  regarded  as  sub  judice. 

Even  if  the  facts  collected  should  cause  the  displacement  hypoth¬ 
esis  to  be  discarded,  the  researches  made  through  its  stimulus  would 
have  served  a  most  useful  purpose  in  establishing  data  for  the  fuller 
comprehension  of  this  problem  of  the  past  history  of  our  planet. 


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Minist.  Agricult.  Argentina,  XIII,  num.  1. 

1919. 

Contribucion  a  la  Geologia  de  la  Region  comprendida  entre  el  Rio 
Negro  y  Arroyo  Valcheta.  Anales.  Minist.  Agricult.  Argentina, 
XIII,  num  4. 

1922. 

Observaciones  Geologicas  en  el  Gran  Bajo  de  San  Julian.  Minist. 
Agricult.  Argentina,  bol.  30,  serie  B. 

Windhausen,  A. 

1916. 

Los  yacimientos  petrollferos  de  la  Zona  Andina.  Minister.  Agricult. 
Argentina,  bol.  15,  serie  B. 

1918. 

The  Problem  of  the  Cretaceous- Tertiary  Boundary  in  South  America, 
Amer.  Journ.  Science,  XLIV,  pp.  1-53. 

128  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 


Windhausen,  A. — Continued. 

1918a.  Rasgos  de  la  historia  geologica  de  la  planicie  costanera  en  la  Patagonia 
septentrional.  Bol.  Acad.  Nacion.  Ciencias,  Cordoba ,  XXIII,  pp. 
319-364. 

1921.  Informe  sobre  un  viaje  de  reconocimiento  geoldgico.  Chubut.  Minist. 

Agricult.  Argent .,  bol.  24,  serie  B. 

1921a.  Ensayo  de  una  clasificacidn  de  los  Elementos  de  Estructura  en  el 
subsuelo  de  la  Patagonia.  Bol.  Acad.  Nacion.  Ciencias,  Cordoba, 
XXV,  pp.  125-139. 

1922.  Estudios  geoldgicos  en  el  valle  superior  del  Rio  Negro.  Minist. 

Agricult.  Argentina,  bol.  29,  serie  B. 

1924.  Lineas  generales  de  la  constitucidn  geoldgica  de  la  Region  situada  al 
oeste  del  Golfo  de  San  Jorge.  Bol.  Acad.  Nacion.  Ciencias,  Cordoba, 
XXVII,  pp.  167-320. 

Woodward,  A.  Smith. 

1908.  On  some  reptilian  bones  from  the  State  of  Rio  Grande  do  Sul.  Final 
Rept.  Brazilian  Coal  Commission,  pp.  202-206;  230-231. 

Woodworth,  J.  B. 

1912.  Geological  Expedition  to  Brazil  and  Chile.  Bull.  Museum.  Compar. 
Zoology,  Harvard  Coll.,  LVl,  no.  1,  geol.  ser.  X,  1. 


Zeiller,  R. 

1895.  Note  sur  la  flore  fossile  des  gisements  houillers  de  Rio  Grande  do  Sul 

(Brezil  meridional).  Bull.  Soc.  Geol.  de  France,  XXIII,  p.  601. 

1896.  Remarques  sur  la  flore  fossile  de  T Altai.  .  .  .  Republique  Argentine 

Bull.  Soc.  Geol.  France,  XXIV,  p.  466. 


APPENDIX 


UPPER  CARBONIFEROUS  FOSSILS  FROM  ARGENTINA 


By 

F.  R.  Cowper  Reed,  M.A.,  Sc.D.,  F.G.S. 
Sedgwick  Museum,  Cambridge ,  England 


With  four  plates 


129 


GENERAL  REMARKS 


The  fossils  submitted  to  me  by  Doctor  Du  Toit  from  the  Que- 
brada  del  Salto,  Barreal,  San  Juan,  Argentina,  are  mostly  preserved 
in  a  tough  purplish  sandy  mudstone  rather  than  shale,  with  an 
irregular  subconchoidal  fracture,  and,  though  often  fragmentary  and 
imperfect,  are  occasionally  in  a  good  state  of  preservation. 

R.  Stappenbeck,1  in  1911,  recorded  the  following  fossils  from  the 
same  locality  and  apparently  from  the  upper  of  the  two  fossiliferous 
horizons  herein  discussed,  which  he  referred  to  the  stage  of  Spirifer 
supramosquensis ,  a  Russian  species  which  Nikitin  regarded  as 
characteristic  of  the  Gshelian : 


Spirifer  supramosquensis  Nik. 
Productus  cor  a  D’Orb. 
Productus  lineatus  Waag. 
Productus  pustulatus  Keys. 
Orthis  sp. 

Chonetes  sp. 


Platy stoma  sp. 

Pleurotomaria  sp. 

Euomphalus  sp.  aff.  parvus  Waag. 
Orthoceras  sp. 

Cyathocrinus  sp. 

Bryozoa. 


No  description  or  figures  of  the  species  were  given,  and  there 
has  not  been,  to  the  best  of  my  knowledge,  any  later  account  of 
the  fauna. 

In  the  succeeding  descriptions  the  figures  7281  to  7376  represent 
the  catalogue  numbers  of  the  specimens,  which  are  preserved  in  the 
South  African  Museum  at  Cape  Town. 


DESCRIPTION 

Fenestella  aff.  perelegans  Meek 

Most  of  the  specimens  of  Fenestella  in  this  collection  are  poorly  preserved 
and  fragmentary  and  only  in  one  case  is  the  poriferous  face  well  preserved. 
In  this  specimen  (7324)  the  branches  are  subparallel,  the  dissepiments 
slender  and  equidistant,  the  fenestrules  rectangular  and  oblong,  being  about 
ip2  times  as  long  as  wide  and  9  to  10  occurring  in  a  distance  of  10  mm.; 
there  are  4  to  5  rather  widely  spaced  small  cells  to  each  fenestrule,  one  of  the 
cells  usually  lying  at  the  base  of  the  dissepiments,  and  the  low  median 
carina  bears  a  row  of  much  smaller  pores  (or  hollow  tubercles)  numbering 
7  to  9  to  each  fenestrule.  The  reverse  face  is  rather  coarsely  striated  longi¬ 
tudinally.  The  poriferous  keel  occurs  in  many  species  of  the  genus  and  was 
figured  by  McCoy2  in  F.  formosa  from  the  Carboniferous  limestone  of 
Ireland.  But  it  is  on  upper  Carboniferous  horizons  that  this  type  of  Fenestella 
is  most  common,  and  we  may  especially  compare  our  form  with  F.  perelegans 
Meek3  of  the  coal  measures  of  Nebraska,  but  also  recorded  by  Waagen  and 

1  Stappenbeck,  Geol.  Aufbau  d.  Vorkordillere,  Geol.  u.  Palaeont.  Abhandl.  N.  F., 
Bd.  IX,  Hefts,  I9ii,pp.  31,32. 

2  McCoy,  Syn.  Carb.  Foss.  Ireland,  1844,  p.  201,  PI.  XXIX,  Fig.  2. 

3Meek  and  Hayden,  Final  Rept.  Nebraska,  1871,  p.  153,  PI.  V II,  Figs.  3  to  3d. 

131 


132  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

Pichl4  from  the  Producius  limestones  of  the  Salt  Range.  There  are  also 
several  allied  Russian  species  from  the  upper  Carboniferous,  such  as  F. 
saraneana  Stuck.5  and  F.  eichwaldi  Stuck.,6  and  the  author7  has  described  a 
form  allied  to  the  latter  species  from  the  upper  Carboniferous  of  Chitral. 
F.  laosensis  Mansuy,8  from  the  Permo-Carboniferous  of  Indo-China,  may 
also  be  compared. 

Fenestella  sp.  ind. 

Among  the  fragments  of  zoaria  of  Fenestella  occurring  in  the  collection 
there  seems  to  be  another  species  (7306,  7307)  characterized  by  its  finer 
mesh-work,  12  to  16  fenestrules  occurring  in  a  distance  of  10  mm.  The 
reverse  face  is  longitudinally  striated,  but  the  poriferous  face  is  unknown 
and  the  affinities  of  the  species  are  therefore  uncertain. 

Polypora  aff.  biseriata  Ulrich 

A  species  of  Polypora  is  represented  by  several  poor  and  fragmentary 
specimens  (7286,  7285,  7311,  7295,  7298).  The  one  (7286)  which  has  the 
celluliferous  face  of  the  zoarium  best  preserved  shows  also  portions  of  the 
reverse  face.  The  zoarium  consists  of  subparallel,  thick,  straight  branches, 
frequently  bifurcating  and  bearing  two  rows  of  rather  large  alternating  cells, 
with  an  additional  one  usually  at  the  base  of  each  dissepiment.  Traces  of 
a  median  line  of  small  nodes  can  be  occasionally  detected.  The  reverse  face  is 
ornamented  with  8  to  10  rather  coarse  longitudinal  thread-like  lines,  and 
is  flattened  for  most  of  its  length,  but  seems  to  swell  up  in  places  into  low, 
broad  nodes.  The  dissepiments  are  short  and  thickened  at  their  base  and 
form  oval  fenestrules  of  subequal  size  longer  than  wide  but  narrower  than 
the  branches;  about  7  occur  in  a  length  of  10  mm. 

The  relations  of  this  imperfectly  known  species  seem  to  be  with  P. 
biseriata  Ulrich9  and  P.  varsoviensis  Prout,10  both  from  the  Warsaw  Forma¬ 
tion,  Illinois. 

Orbiculoidea  saltensis  sp.  nov.  (Plate  XIII,  Fig.  1) 

Shell  subcircular.  Upper  valve  low,  conical,  with  excentral  apex  situ¬ 
ated  at  about  one-third  of  the  diameter  from  posterior  margin.  Surface 
ornamented  with  about  fifteen  coarse  rounded  subequidistant  concentric 
liras,  mostly  bearing  small,  low,  closely  placed,  hollow  tubercles,  the  whole 
crossed  by  very  delicate  radial  strias.  Lower  valve  (incompletely  known) 
flattened  or  gently  concave,  with  hollow,  low,  conical  apex  and  a  small 
foramen  at  the  end  of  a  partly  inclosed  broad  groove  to  posterior  margin. 

Dimensions — I  (7335):  Diameter,  20  mm.;  height,  c.  8  mm.  II  (7340): 
Diameter,  c.  27  mm. ;  height,  c.  9  mm. 

Remarks — There  are  three  specimens  (7335,  7340,  7310)  of  this  new 
species,  one  of  which  (7335)  has  the  lower  valve  showing  the  posterior 
groove,  though  in  a  poor  state  of  preservation.  The  other  two  are  less  perfect 
and  only  show  the  upper  valve.  The  peculiar  tuberculation  of  the  concentric 
rugae  seems  to  be  an  original  and  definite  character,  but  it  is  only  well  seen 

4Waagen  and  Pichl,  Salt-Range  Foss.  (Palseont.  Ind.,  Ser.  XII,  1885),  p.  777;  PI. 

LXXXVII,  Figs.  1  to  3. 

6  Stuckenberg,  Mem.  Com.  Geol.  Russ.,  vol.  X,  no.  3,  1895,  p.  231,  t.  XX,  Fig.  16. 

6  Ibid.,  p.  234,  t.  XXII,  Fig.  1. 

7 Reed,  Upper  Carb.  Foss.  Chitral  (Palasont.  Ind.,  n.s.,  vol.  VI,  mem.  4,  1925),  p.  19, 
pi.  II,  Figs.  6,  6 a,  7. 

8  Mansuy, Mem.  Serv.  Geol.  Indo-Chine,  vol.  II,  fasc.  4, 1913,  p.  23,  PI.  I,  Figs.  2 a  to  c . 

9  Ulrich,  Geol.  Surv.  Illinois,  vol.  8,  1890,  p.  592,  pi.  LX,  Figs.  4,  4 a  and  4 b. 

10  Ibid.,  p.  593,  PI.  LX,  Figs.  2,  2 a,  and  2 b. 


UPPER  CARBONIFEROUS  FOSSILS  FROM  ARGENTINA 


133 


in  two  specimens,  the  third  (7310)  being  much  crushed  and  distorted.  The 
relations  of  this  species  seem  to  be  with  Orbiculoidea  missouriensis  (Shu- 
mard)11  of  the  upper  Carboniferous  rather  than  with  0.  nitida  Phill. 

Productus  lineatus  Waagen  (Plate  XIII,  Fig.  9) 

This  species,12  which  is  included  by  many  authors  in  Productus  cor  a 
D’Orb.,  is  represented  by  one  small  complete  specimen  of  a  pedicle  valve 
(7365)  and  several  fragments  of  larger  shells.  The  synonymy  of  this  species 
has  frequently  been  discussed,13  but  to  the  author14  Waagen’s  type  seems  at 
any  rate  to  mark  a  distinct  variety  of  the  form  known  as  Productus  cora  in 
the  lower  Carboniferous  of  Europe. 

Productus  curvirostris  Scliellwien  var.  nov.  barrealensis  (Plate  XIII,  Figs.  4 a,  4 b) 

Shell  with  strongly  convex  narrow,  elongated  pedicle-valve,  having 
prominent  incurved  acutely  pointed  beak  projecting  behind  and  over  short 
straight  hinge-line.  Ears  small,  triangular,  gently  convex,  well  marked 
off  from  body  by  impressed  line.  Surface  of  valve  ornamented  with  few 
regularly  distributed  spinose  tubercles,  semirecumbent,  widely  spaced,  and 
arranged  in  a  roughly  quincunx  order,  with  weak  concentric  rugae  becoming 
more  marked  on  the  flanks  and  with  fine,  irregular,  undulating  concentric 
lamellose  striae  over  the  whole  valve. 

Dimensions — (7315):  Length,  16  mm.;  width  (cardinal),  10  mm.; 
height,  c.  8  mm. 

Remarks — This  shell,  which  is  represented  by  one  well-preserved  speci¬ 
men  of  a  pedicle-valve  (7315)  and  by  a  fragment  of  another  may  be  regarded 
as  a  variety  of  Productus  curvirostris  Schellw.15  of  the  Permo-Carboniferous 
of  Italy.  Mansuy16  has  also  recorded  this  species  from  Indo-China.  It  is 
undoubtedly  allied  to  Pr.  acute atus  Mart.,  but  is  sufficiently  distinct,  as 
Schellwien  and  others  have  pointed  out. 

Productus  cf.  juresanensis  Tschernyschew 

A  fragment  of  a  pedicle- valve  of  a  species  of  Productus  (7281)  is  too 
imperfect  for  a  satisfactory  determination,  but  it  appears  to  possess  the 
ornamentation  of  Pr.  juresanensis  Tschern.,17  and  it  may  be  compared  with 
it  rather  than  with  Pr.  nebrascensis  Owen,18  which  is  closely  allied  and  is 
also  an  upper  Carboniferous  species.  Pr.  scabriculus  Mart,  belongs  to  the 
same  group. 

Productus  ( Marginifera )  cf.  echinatus  Waagen 

One  imperfect  pedicle  valve  (7364)  appears  to  possess  the  external  char¬ 
acters  of  Pr.  (. Marginifera )  echinata  Waagen,19  as  figured  by  Waagen  from 

uSchuchert,  Bull.  87  U.  S.  Geol.  Surv.,  1897,  p.  280  (for  synonymy  and  references). 

12  Waagen,  Salt  Range  Foss.  I  (Palaeont.  Ind.),  p.  673,  PI.  LXVI,  Figs.  1,  2;  PI. 
LXVII,  Fig.  3. 

13Hayasaka,  Science  Rept.  Tohoku  Imper.  Univ.,  ser.  2,  Geol.,  1922,  pp.  86-93, 

14 Reed,  Up.  Carb.  Foss.  Chitral,  etc.,  Palaeont.  Ind.,  vol.  VI,  mem.  no.  4,  1925,  p.  28, 
PI.  Ill,  Figs.  12  to  14a. 

15  Schellwien,  Palaeontographica,  XXXIX,  1902,  p.  26,  t.  Ill,  Figs.  12  to  14.  Gortani, 
Palaeont.  Ital.,  vol.  XII,  1906,  p.  23,  t.  II,  Figs.  1  to  3;  id.,  Boll.  Soc.  Geol.  Ital.,  vol.  XXV, 
1906,  fasc.  2,  p.  14,  Fig.  7. 

16  Mansuy,  Mem.  Serv.  G60I.  Indo-Chine,  vol.  II,  fasc.  4,  1913,  p.  32,  PI.  II,  Figs. 
9a  toe;  ibid.,  vol.  Ill,  fasc.  3,  1914,  p.  16,  PI.  II,  Figs,  ioatoc. 

17  Tschernyschew,  Mem.  Com.  G60I.  Russ.,  vol.  XVI,  no.  2, 1902,  p.  620,  t.  XLVII, 
Figs.  1,  2;  t.  LIII,  Fig.  4. 

18Schuchert,  Bull.  87  U.  S.  Geol.  Surv.,  1897,  p.  327  (for  synonymy  and  references). 

14  Waagen,  op.  cit.,  p.  727,  PI.  LXXVIII,  Fig.  1. 


134  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

the  lower  Productus  limestone  of  the  Salt  Range.  The  thin,  recumbent 
spines  on  the  surface,  becoming  more  upstanding  or  tubercular  posteriorly, 
and  the  transverse  swollen  shape  of  the  valve  are  clearly  preserved;  the 
broad  short  beak,  hollowed  umbonal  slopes,  and  hinge-line  can  also  be 
distinguished.  It  had  been  labeled  Strophalosia  cf.  indica  Waag.,  but  is 
totally  different  from  that  species. 

Productus  ( Marginifera )  spinulo-costatus  Abich  var.  nov.  peregrina  (Plate  XIII,  Fig.  2) 

There  is  one  fairly  perfect  pedicle- valve  (7374)  which  might  be  regarded 
as  a  variety  of  Productus  ( Marg .)  ornatus  Waag.,20  but  seems  more  allied  to 
Pr.  (Marg.)  spinulo-costatus  Abich,21  of  the  Djulfa  beds,  and  if  better  known 
we  might  consider  it  to  be  a  distinct  species.  The  shell  is  transversely  semi¬ 
elliptical,  with  a  straight  hinge-line,  equal  to,  or  nearly  equal  to,  its  width; 
the  pedicle-valve  is  strongly  swollen,  with  a  weak,  broad  median  depression 
down  the  middle;  the  beak  is  broad,  rounded,  obtuse,  swollen,  and  incurved 
and  overhangs  the  hinge-line.  The  ears  are  small,  triangular,  depressed, 
and  sharply  marked  off  from  the  umbonal  slopes,  which  descend  steeply  to 
them  and  are  somewhat  excavated.  The  surface  of  the  valve  is  ornamented 
with  weak,  low,  rounded,  indistinct  ribs,  somewhat  discontinuous,  being 
mainly  due  to  radially  elongated  recumbent  stout  spines  arranged  in  a 
roughly  quincunx  fashion,  but  widely  spaced;  there  are  about  eight  such 
faint  ribs  on  each  side  of  the  median  depression,  which  bears  only  one  short 
similar  rib  arising  at  about  half  the  length  of  the  valve ;  three  to  five  small  spi- 
nose  tubercles  form  an  irregular  line  along  the  junction  of  the  ears  with  the 
body,  and  two  to  three  more  occur  on  the  ears.  Fine  concentric  striae  cross 
the  valve,  with  a  few  stronger  growth-lines  becoming  more  marked  on  the 
flanks. 

From  typical  examples  of  Pr.  (Marg.)  ornatus  it  differs  by  its  more 
elongated  recumbent  spine  bases,  and  thus  more  resembles  the  Armenian 
species,  Pr.  (Marg.)  spinulo-costatus ,  which  Freeh22  and  Hayasaka23  figure 
also  from  China.  Pr.  walcottianus  Girty24  may  also  be  compared. 

Chonetes  cf.  pseudovariolata  Nikitin 

Two  small  specimens  of  Chonetes  in  rather  a  poor  state  of  preservation 
seem  to  be  comparable  to  Ch.  pseudovariolata  Nikitin,25  of  the  Gshelian  stage 
of  Russia,  rather  than  with  Ch.  lissarensis  Diener,26  of  the  Zewan  beds  of 
Kashmir;  but  such  small  and  imperfectly  known  shells  are  almost  impossible 
to  determine  specifically. 

Chonetes  granulifer  Owen  (Plate  XIII,  Fig.  6) 

One  large  specimen  of  a  species  of  Chonetes  (7319)  shows  the  pedicle- 
valve  with  the  shell  broken  away  from  most  of  the  middle  part  and  the 
outer  surface  only  preserved  on  a  small  portion  near  the  anterior  margin. 
It  is  transversely  semi-elliptical  in  shape,  with  the  cardinal  angles  slightly 

20  Waagen.  op.  cit.,  p.  721,  PI.  LXXVII,  Figs.  5  and  6. 

21  Freeh  and  Arthaber,  Palaeoz.  in  Hocharmenien,  Beitr.  z.  Palaeont.  u.  Geol.  Oesterr. 
Ung.,  Bd.  XII,  1900,  pp.  262-264,  t.  XX,  Figs.  5,  7, 8,  and  9;  Diener,  Palaeont.  Ind.,  n.s., 
vol.  V,  mem.  2,  1915,  p.  82,  PI.  VIII,  Figs.  13,  a  to  d,  PI.  IX,  Figs.  1  and  2. 

22 Freeh  in  Richthofen’s  “China,”  Bd.  V,  1911,  p.  175,  PI.  XXVII,  Fig.  2. 

23  Hayasaka,  Science  Rept.  Tohoku  Imper.  Univ.  Ser.  2,  Geol.,  1922,  p.  99,  PI.  IV, 
Figs.  15  and  16. 

24 Girty,  Prof.  Paper  58,  U.  S.  Geol.  Surv.,  1908,  p.  269,  PI.  XXI,  Figs.  27,  a  and  b. 

“Nikitin,  Mem.  Com.  Geol.  Russ.,  vol.  V,  no.  5,  1890,  p.  27,  PL  II,  Figs.  1  to  4; 
Loczy,  Beschr.  Palaeont.  Stratigr.  Result.  Reise  Graf.  Bela  Szechenyi  in  Ostasien 
(Budapest,  1898),  p.  73,  t.  Ill,  Figs.  8  to  13. 

26  Diener,  Himal.  Foss.  (Palaeont.  Ind.  Ser.  XV),  vol.  I,  pt.  4,  1897,  p.  19,  PI.  II, 
Figs.  4  and  6;  ibid.,  n.s.,  vol.  V,  mem.  2,  1915,  p.  83,  PI.  IX,  Fig.  3. 


UPPER  CARBONIFEROUS  FOSSILS  FROM  ARGENTINA 


135 


pointed  but  not  produced  into  ears.  The  cardinal  margin  shows  seven  to 
eight  small,  obliquely  directed  spine-bases,  the  largest  being  at  the  cardi¬ 
nal  angle.  The  body  is  gently  convex,  and  the  valve  is  not  definitely  flat¬ 
tened  or  depressed  in  the  middle,  a  sinus  being  completely  wanting.  The 
surface  is  covered  with  numerous  fine,  granulated,  equal  radial  lines,  fifty  to 
sixty  occurring  on  the  margin  in  a  space  of  io  mm.,  apparently  increasing  by 
bifurcation  and  intercalation,  and  in  all  there  must  be  at  least  200  such  lines 
around  the  whole  margin  of  the  valve.  The  interior  shows  a  low,  narrow 
median  ridge  extending  from  the  beak  for  about  one-third  the  length  of  the 
valve,  and  separating  weakly  impressed  flabellate  diductor  scars,  on  each 
side  and  in  front  of  which,  to  a  distance  of  about  three-fourths  the  radial 
diameter  of  the  valve,  there  are  coarse,  rather  closely  set  papillae,  somewhat 
irregularly  arranged  in  radial  lines ;  outside  them  there  is  a  marginal  band 
of  smaller,  more  regular,  closer,  and  more  numerous  papilla  (in  both  cases, 
of  course,  shown  on  the  internal  cast  as  punctae) . 

This  shell  in  some  respects  seems  to  resemble  Ch.  variolata  D ’Orb., 27 
and  especially  its  variety  baroghilensis  Reed28  from  the  upper  Carboniferous 
of  Chitral,  in  its  internal  character,  but  it  has  no  definite  median  flattening 
or  sinus.  Many  of  the  shells  referred  to  Ch.  granulifer  Owen29  bear  a  closer 
resemblance  to  our  shell,  though  this  specific  name  has  been  used  in  some¬ 
what  a  wide  sense  and  still  requires  a  detailed  diagnosis  and  strict  limita¬ 
tion,  but  it  is  an  indication  of  an  upper  Carboniferous  horizon. 

Camarophoria  cf.  mutabilis  Tschemyschew? 

Two  crushed  and  imperfect  valves  (7327,  7352)  of  a  rhynchonelloid 
shell  having  three  to  four  ribs  in  the  sinus  and  on  the  fold  and  four  to  five  on 
each  side  seem  to  be  comparable  with  the  variable  species  Camarophoria 
mutabilis  Tschem.,30  typically  occurring  on  the  Schwagerina  horizon  of 
Russia  and  also  recorded  from  Indo-China  by  Mansuy.31 

Spirifer  cf.  supramosquensis  Nikitin  (Plate  XIV,  Fig.  1) 

Stappenbeck32  has  already  recorded  Spirifer  supramosquensis  from  this 
locality  in  Argentina.  It  is  characteristic  of  the  Gshelian,  according  to> 
Nikitin.33  There  is  one  specimen  (7316)  in  the  present  collection  which, 
seems  indistinguishable  from  this  species,  and  especially  resembles  the 
figure  of  the  shell  from  the  Urals  referred  by  De  Verneuil34  to  Sp.  crassus 
De  Ron.,  but  considered  by  Nikitin  to  be  identical  with  Sp.  supramosquen¬ 
sis.  The  shells  which  Hayasaka35  and  Mansuy36  respectively  figure  as  Sp. 
nikitini  Tschern.  from  the  upper  Carboniferous  of  Manchuria  (in  associ¬ 
ation  with  Sp.  supramosquensis)  and  from  the  Productus  limestone  of  Indo- 
China  bear  a  considerable  resemblance,  and  Hayasaka  remarks  on  its  like¬ 
ness  to  the  American  Sp.  mexicanus  Shum.  of  the  upper  Carboniferous. 

27D’Orbigny,  Voyage  dans  l’Amerique  Merid.  Ill,  pt.  4,  1842,  p.  49,  PI.  IV,  Figs.  10 
and  11.  Kozlowski,  Brach.  Carb.  Super.  Bolivie,  Ann.  Pateont.  IX,  1914,  p.  55,  PI. 
VIII,  Fig.  16. 

28  Reed,  Up.  Carb.  Foss.  Chitral  (Pal.  Ind.,  n.s.,  vol.  VI,  mem.  4,  1925),  p.  40,  PI.  Ill, 
Figs.  1  to  4. 

29  Greene,  Journ.  Geol.,  vol.  XVI,  1908,  pp.  654-663,  Pis.  I-IV ;  Girty,  Bull.  544,  U.  S. 
Geol.  Surv.,  1915,  p.  59,  PI.  VI,  Figs.  12  to  133. 

30  Tschemyschew,  op.  cit.,  p.  491,  t.  XLV,  Figs.  1  to  15. 

31  Mansuy,  op.  cit.,  vol.  II,  fasc.  4,  p.  90,  PI.  IX,  Figs.  14a  to  c. 

32  Stappenbeck,  Geol.  Aufb.  d.  Vorkordillere  (Geol.  u.  Palaeont.  Abh.  N.  F.,  Bd.  IX, 
Heft  5,  1911),  pp.  31-32. 

33  Nikitin,  Mem.  Com.  G60I.  Russ.,  vol.  V,  no.  5, 1890,  pp.  66,  165,  t.  Ill,  Figs.  1  to  3. 

34  De  Verneuil,  Geol.  Russ.  II,  Palaeont.,  p.  165,  t.  VI,  Fig.  2.  v- 

33  Hayasaka,  op.  cit.,  1922,  p.  125,  PI.  VI,  Figs.  10  to  13. 

36  Mansuy,  Mem.  Serv.  Geol.  Indo-Chine,  vol.  2,  fasc.  4, 1913,  p.  66,  PI.  VI,  Fig.  4. 


136  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

Gortani37  would  regard  Sp.  fritschi  Schellw.  as  only  a  variety  of  Sp.  supra- 
mosquensis ,  and  there  are  many  closely  allied  species  from  the  upper  Carbon¬ 
iferous  of  Russia,  such  as  Sp.  ussensis  Stuck.,38  which  are  difficult  to  separate. 

Spirifer  mexicanus  Shumard  var.  nov.  neotropica  (Plate  XIV,  Figs.  3,  4) 

There  are  two  specimens  (7325,  7366)  of  a  species  of  Spirifer  belonging 
to  the  Sp.  mexicanus  group  which  much  resemble  the  varieties  of  Sp. 
mexicanus  from  Texas,  figured  by  Girty,39  and  are  distinguished  by  the 
more  definitely  demarcated  but  smooth  channel  in  the  median  sinus  of  the 
pedicle- valve.  This  median  channel  in  the  sinus  of  one  of  our  specimens 
is  deep,  narrow,  devoid  of  ribs,  and  preserves  an  almost  uniform  width, 
but  in  the  other  (7366)  is  more  open.  The  shell  is  longer,  more  oval,  and 
narrower  in  shape  than  Sp.  supramosquensis ,  being  longer  than  wide,  with 
a  shorter  hinge-line  and  smaller  beak.  The  interior  of  part  of  the  valve  is 
seen  in  one  specimen  and  shows  rather  coarse  pitting  toward  the  lateral 
margins  on  each  side  of  the  large  median  muscular  area.  There  are  seven 
to  ten  low,  rounded,  flattened,  simple  ribs  of  subequal  size  on  each  lateral 
lobe,  and  on  the  rounded  slopes  of  the  sinus  there  are  three  or  four  nar¬ 
rower  equal  similar  ribs,  and  on  the  upper  edge  two  much  sharper  ones. 
The  cardinal  ribs  are  very  faint.  Very  fine  radial  lines  and  delicate  con¬ 
centric  striation  ornament  the  whole  surface  of  the  shell. 

Dimensions — Length,  c.  25  mm.;  width,  c.  30  mm. 

Remarks — In  spite  of  its  more  quadrate  shape  and  simple  ribs  it  seems 
probable  that  this  shell  is  more  allied  to  Sp.  mexicanus  than  to  Sp.  nikitini 
Tschern.,40  but  it  is  certainly  a  new  variety. 

Spirifer  wynnei  Waagen  var.  nov.  argentina  (Plate  XIV,  Figs,  ya,  7 b) 

Shell  transversely  subelliptical,  about  twice  as  wide  as  long;  hinge-line 
less  than  width  of  shell;  cardinal  angles  rounded.  Pedicle- valve  convex, 
deeper  than  opposite  valve;  beak  prominent,  moderately  high,  somewhat 
incurved;  hinge-area  triangular,  gently  concave,  inclined  steeply  to  plane 
of  valve,  well-defined  from  lateral  lobes  by  sharp  edges;  surface  of  valve 
crossed  by  shallow,  broad,  rounded  median  sinus,  not  sharply  marked  off 
from  lateral  lobes,  increasing  in  width  and  depth  anteriorly,  with  floor  pro¬ 
duced  with  broad,  rounded,  projecting  tongue  arching  steeply  upward,  so 
as  to  be  nearly  at  right  angles  to  plane  of  valve;  lateral  lobes  rounded,  gently 
to  strongly  convex  from  side  to  side.  Sinus  holding  nine  to  ten  subequal, 
narrow,  low,  rounded  ribs,  which  mostly  divide  at  about  half  their  length, 
making  fifteen  to  eighteen  on  the  anterior  margin.  Lateral  lobes  with  ten  to 
•twelve  similar,  rather  larger  ribs,  which  bifurcate  once  at  about  half  their 
length  and  sometimes  again  nearer  margin,  or  rarely  trifurcate,  giving  an 
appearance  of  fasciculation  and  numbering  twenty-four  to  twenty-eight  of 
subequal  size  on  the  margin,  those  near  the  cardinal  edge  becoming  smaller 
and  fainter.  Brachial  valve  less  convex  and  shallower  than  pedicle- valve, 
with  low,  broad,  rounded  median  fold  increasing  in  width  anteriorly,  not 
marked  off  from  lateral  lobes;  beak  small,  slightly  elevated,  scarcely 
incurved;  hinge-area  narrow,  with  sharply  defined  edges,  lying  in  plane  of 
valve.  Fold  with  five  to  seven  narrow,  low,  rounded  ribs,  arising  from  the 
beak,  and  each  bifurcating  at  about  one-third  to  one-half  its  length,  and 

37  Gortani,  Palseont.  Ital.,  vol.  XII,  1906,  p.  26,  t.  II,  Figs.  15  to  18. 

38  Stuckenberg,  Mem.  Com.  G60I.  Russ.,  n.s.,  Liv.  23, 1905,  pp.  44,  123,  t.  Ill,  Fig.  17; 
t.  V,  Figs.  3  and  4;  t.  VII,  Fig.  11. 

39  Girty,  Prof.  Paper  58,  U.  S.  Geol.  Surv.,  1908,  p.  360,  PI.  XIII,  Figs.  1  to  9. 

40  Tschemyschew,  op.  cit.,  p.  542,  t.  XIII,  Fig.  2. 


UPPER  CARBONIFEROUS  FOSSILS  FROM  ARGENTINA 


137 


•some  dividing  a  second  time  so  as  to  form  sixteen  to  eighteen  ribs  on  the 
front  margin.  Lateral  lobes  with  five  to  six  similar  but  rather  larger  ribs  on 
each  side,  which  bifurcate  soon  after  their  origin  and  mostly  again  at  about 
half  their  length  or  near  the  margin,  so  as  to  make  about  twenty  to  twenty- 
four  in  all  on  the  margin,  with  a  decided  tendency  to  fasciculation.  In  both 
valves  the  ribs  on  the  fold  and  in  the  sinus  tend  to  be  smaller  than  those 
on  the  lateral  lobes. 

Dimensions — (7309):  Length  of  brachial  valve,  31  mm.;  width  of  bra¬ 
chial  valve,  50  to  54  mm. ;  depth  of  conjoint  valves,  26  mm. 

Remarks — This  form,  which  is  represented  by  five  imperfect  specimens 
in  different  states  of  preservation,  is  undoubtedly  closely  allied  to  Sp. 
wynnei  Waagen,41  but  it  can  hardly  be  considered  identical  with  the  Salt 
Range  type-examples,  though  it  may  be  regarded  as  a  variety.  The  chief 
differences  are  in  the  tendency  to  fasciculation  of  the  ribs  and  in  the  fact 
that  they  are  smaller  on  the  fold  and  sinus  than  on  the  lateral  lobes.  The 
rounded  character  and  low  elevation  of  the  fold  on  the  brachial  valve  and 
the  sharply  demarcated  hinge-area  on  the  pedicle-valve  are  features  which 
distinguish  it  from  another  Salt  Range  species,  Sp.  oldhamianus  Waag.  ;42 
the  number  of  ribs  is  also  less.  The  lower  Carboniferous  species  Sp.  crassus 
De  Kon.43  is  perhaps  allied  to  our  shell,  but  it  has  a  less  marked  median  fold 
and  sinus,  and  no  tendency  to  fasciculation  of  the  ribs.  Some  of  the  shells 
which  from  time  to  time  have  been  referred  to  Sp.  striatus  Mart,  show 
a  marked  resemblance  in  the  ribbing,  but  differ  by  not  possessing  rounded 
cardinal  angles,  which  is  also  one  of  the  chief  distinctions  of  our  shell  from 
the  true  Sp.  cameratus  Morton,  though  Derby44  attributed  some  Brazilian 
shells  of  this  shape  to  this  species.  The  fine-ribbed  specimens  from  the  British 
lower  Carboniferous  which  Davidson45  at  first  referred  to  Sp.  duplicicosta 
Phill.  but  subsequently46  transferred  to  Sp.  striatus  are  almost  inseparable 
from  our  shells,  but  the  present  author  does  not  agree  with  Davidson’s  views 
-about  the  species.  Sp.  volgensis  Stuck.47  from  the  Russian  upper  Carbonif¬ 
erous  may  also  be  compared.  Diener48  has  figured  and  described  examples 
of  Sp.  wynnei  from  Chitichun,  which  much  resemble  our  specimen.  The 
species  which  Nikitin49  described  from  the  Gshelian  of  Russia  as  Sp.  post- 
striatus  was  referred  in  1889  by  Tschemyschew  to  Sp.  wynnei  (but  subse¬ 
quently  in  1902  to  Sp.  cameratus ) ;  it  differs  from  our  shell  by  having  a  more 
triangular  shape  and  longer  hinge-area,  the  latter  extending  to  the  cardinal 
-angles  instead  of  being  considerably  less  than  the  width  of  the  shell.  The 
ribbing,  however,  of  Sp.  poststriatus  is  more  like  that  of  our  shell  than  is  that 
of  Sp.  wynnei ,  being  subfasciculate.  Undoubtedly  our  shell  belongs  to  the 
same  group  as  that  containing  Sp.  striatus ,  Sp.  duplicicosta ,  Sp.  cameratus , 
Sp.  condor ,  Sp.  fasciger,  Sp.  ravana,  and  Sp.  marcoui ,  all  of  which  are 
recorded  by  Tschemyschew50  from  the  upper  Carboniferous  of  Russia. 
Hayasaka,51  who  describes  Sp.  wynnei  from  the  upper  Carboniferous  of 

41  Waagen,  Salt  Range  Foss.,  I,  p.  517,  PI.  XLIV,  Figs.  6  and  7 

42  Ibid.,  I,  p.518,  Pl.XLVI. 

43  De  Koninck,  Faune  Calc.  Belg.,  VI  (Ann.  Mus.  R.  Belg.,  XIV,  1887),  p.  137, 
PI.  XXIII,  Figs.  3  to  9. 

44  Derby,  Bull.  Cornell  Univ.,  1874,  p.  12,  PI.  I,  Fig.  9  (non  cet.). 

45  Davidson,  Mon.  Brit.  Foss.,  Brach.  II,  p.  21,  PI.  Ill,  Figs.  7  to  9. 

*6Ibid.,  p.  221. 

47  Stuckenberg,  Mem.  Com.  Geol.  Russ,  n.s.,  Livr.  23,  1905,  pp.  40,  122,  t.  Ill,  Fig.  19. 

48  Diener,  Himal.  Foss.,  vol.  1,  pt.  3  (Palaeont.  Ind.  Ser.  XV.)  1897,  p.  44,  PI.  VII, 
Figs.  1  to  4. 

49  Nikitin,  op.  cit.,  1890,  pp.  64,  164,  t.  II,  Figs.  16  to  19. 

50  Tschemyschew,  op.  cit.,  1902,  pp.  133-146. 

61  Hayasaka,  op.  cit.,  1922,  p.  'I27,  PI.  VI,  Figs.  15  and  16. 


138  GEOLOGICAL  COMPARISON  OP  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

Manchuria,  notes  points  of  resemblance  between  it  and  Sp.  volgensis  Stuck. 
It  is  said  also  to  occur  in  the  “lower  Permian”  of  Australia,  according  to 
Freeh,  and  in  the  upper  Carboniferous  of  California,  and  Schellwien52- 
figures  it  from  the  Trogkofel  beds  of  the  C-arnic  Alps. 

Spirifer  saltensis  sp.  nov.  (Plate  XIV,  Figs.  8a,  8b) 

Shell  transversely  elliptical,  much  compressed;  cardinal  angles  strongly 
rounded;  cardinal  line  less  than  width  of  shell.  Pedicle- valve  gently  convex, 
most  so  posteriorly;  beak  small,  pointed,  elevated,  incurved,  with  concave 
shoulders;  hinge  area  small,  triangular,  nearly  in  plane  of  valves,  with 
sharply  defined  edges.  Surface  of  valve  with  weak,  broad,  shallow,  but 
well-defined,  rounded  sinus  holding  four  to  five  narrow,  low,  rounded, 
simple,  equal  ribs;  lateral  lobes  covered  with  eight  to  nine  much  broader, 
low,  rounded,  flattened  ribs,  becoming  narrower  toward  the  cardinal  angles, 
and  each  dividing  near  the  margin  into  two,  or  usually  three,  much  smaller 
ribs,  giving  a  subfasciculate  appearance.  Brachial  valve  less  convex  than 
pedicle-valve,  with  a  low,  scarcely  raised,  but  definite  broad  median  fold, 
increasing  rather  rapidly  in  width  and  carrying  a  median  weak,  narrow, 
simple  rib,  and  on  each  side  of  it  a  stronger  but  narrow,  rounded,  bifurcated 
rib,  the  division  taking  place  at  about  the  third  of  its  length;  lateral  lobes 
with  six  to  seven  much  broader,  low,  flattened  ribs  dividing  into  three 
smaller  ones  near  the  margin,  and  clearly  forming  fascicles;  toward  the 
cardinal  margin  all  the  ribs  become  very  weak  and  faint. 

Dimensions — (7296) :  Length,  20  mm. ;  width,  29  mm. ;  thickness,  10 mm. 

Remarks — The  relations  of  this  shell,  of  which  there  is  only  one  speci¬ 
men  which  is  fortunately  nearly  perfect,  are  undoubtedly  with  the  earner  a- 
tus  group  of  species;  the  fasciculation  of  the  ribs  is  a  distinctive  feature. 
The  rounded  elliptical  shape  of  the  shell  and  short  hinge-line  are  unlike 
Sp.  fasciger  or  its  allies,  although  the  ribbing  especially  recalls  some  forms 
attributed  to  Sp.  musakheylensis  Dav.,63  which  is  often  regarded  as  only  a 
variety  of  Sp.  fasciger.5*  But  the  elliptical  shape,  rounded  cardinal  angles, 
and  short  hinge-line  are  found  combined  with  a  similar  division  and  sub- 
fasciculation  of  the  ribs  in  some  shells  referred  by  Davidson 55  to  Sp.  dupli - 
cicosta  Phill.  from  the  British  lower  Carboniferous,  and  to  Sp.  cameratus 
Morton  from  Brazil,56  of  which  species  our  shell  might  even  be  considered 
a  variety. 

Spirifer  barrealensis  sp.  nov.  (Plate  XIV,  Fig.  2) 

Shell  transversely  subtriangular.  Pedicle-valve  convex,  with  deep,  well- 
defined  median,  subangular  sinus,  increasing  slowly  in  width  to  front  margin ; 
hinge-line  long,  equal  to  width  of  valve;  cardinal  angles  acute;  beak  high, 
prominent,  acutely  pointed,  incurved;  hinge-area  high,  triangular,  concave, 
nearly  in  plane  of  valve.  Surface  of  shell  marked  with  five  to  six  low,  rounded, 
simple,  weak  ribs  on  each  lateral  lobe,  becoming  fainter  and  almost  obsolete 
toward  the  cardinal  angles ;  sinus  with  lateral  slopes  bearing  a  faint,  low 
narrower  rib  on  each  side,  arising  at  about  half  the  length  of  the  valve  by  the 
unequal  division  of  the  larger  rib  forming  the  edge  of  the  sinus,  the  floor  of 

62  Schellwien,  Fauna  d.  Trogkofelsch.,  Abh.  k.  k.  geol.  Reichsanst.,  XVI,  1900,  p.  75, 
t.  X,  Figs.  5  and  6. 

63  Diener,  Himal.  Foss.,  vol.  I,  pt.  4,  p.  35,  PI.  Ill,  Figs.  3  and  4;  PI.  IV,  Figs.  I  and 
2;  PI.  V,  Fig.  1. 

64  Reed,  Upper  Carb.  Foss.  Chitral,  Palaeont.  Ind.,  n.s.,  vol.  VI,  mem.  4,  1925,  p.  42 
and  references. 

65  Davidson,  op.  cit.,  PI.  II,  Fig.  11  (non  cet.). 

66  Derby,  op.  cit.,  p.  12,  PI.  I,  Figs.  3,  14  (non  cet.). 


UPPER  CARBONIFEROUS  FOSSILS  FROM  ARGENTINA 


139 


the  sinus  being  narrow,  concave,  and  the  width  of  a  rib.  Whole  surface  of 
valve  covered  with  closely  placed  concentric  lamellose  striae  and  growth¬ 
lines,  and  with  very  delicate  radial  striae.  Brachial  valve  unknown. 

Dimensions — (7371):  Length,  c.  17.5  mm.;  width,  c.  32.0  mm. 

Remarks — The  affinities  of  this  species  seem  to  be  with  Sp.  aff.  boon - 
ensis  Swallow,  described  by  Girty57  from  Oklahoma.  The  one  specimen  in 
the  present  collection  is  crushed  and  imperfect,  only  the  central  portion 
and  left  lateral  lobe  of  the  pedicle-valve  being  preserved.  Sp.  keilhavii 
Von  Buch58  from  the  upper  Carboniferous  of  the  Urals,  etc.,  is  less  like  it. 

Spirifer  aff.  rajah  Salter  (Plate  XIV,  Fig.  5) 

There  is  one  imperfect  specimen  (7317)  of  a  pedicle-valve  of  a  species  of 
Spirifer  which  may  be  a  variety  of  Sp.  barrealensis,  but  it  differs  in  being 
subquadrate  in  shape,  in  possessing  more  numerous  and  narrower  ribs  on 
the  lateral  folds,  and  by  having  on  the  steeply  inclined,  flattened  slopes  of 
the  sinus  two  to  three  very  faint  and  narrower  ribs ;  the  floor  of  the  sinus 
is  flattened,  of  nearly  uniform  width,  and  rather  wider  than  one  of  the 
inner  ribs  on  the  lateral  lobes,  just  as  in  Sp.  barrealensis.  The  minute 
ornamentation  is  identical.  In  our  specimen  the  anterior  part  of  the  shell 
is  sharply  bent  under  the  posterior  part,  but  the  sinus,  with  its  short  pro¬ 
jecting  tongue,  and  the  concentric  lamellae  near  the  edge,  are  well  pre¬ 
served,  and  it  is  in  this  region  that  the  ribbing  is  most  clearly  shown.  The 
cardinal  angles  are  obtusely  angular,  and  the  shell  much  resembles  certain 
of  the  specimens  figured  by  Broili59  from  Timor,  which  he  refers  to  the 
Himalayan  species  Sp.  rajah  Salter.  Sp.  samarensis  Stuck,  is  also  allied. 

Spirifer  ( Martinia )  cf.  simensis  Tschernyschew  (Plate  XIV,  Fig.  6) 

There  are  two  specimens  of  pedicle- valves  in  the  collection  (7338,  7363) 
which  seem  comparable  to,  if  not  identical  with,  the  shell  figured  and 
described  by  Tschernyschew60  from  the  Schwagerina  horizon  in  the  Urals 
under  the  name  Martinia  simensis.  Mansuy61  has  recorded  this  species 
from  Tonkin. 

Dimensions — (7363) :  Length,  c.  15  mm.;  width,  c.  15  mm. 

Spirifer  ( Martiniopsis )  cf.  aschensis  Tschernyschew 

An  imperfect  pedicle- valve  (7361)  which  shows  the  umbo,  the  median 
channel-like  sinus,  and  the  faint  ribs  on  the  lateral  lobes,  may  be  compared 
with  Tschernyschew’ s  Martiniopsis  aschensis 62  rather  than  with  any  of  the 
other  closely  allied  species  of  the  same  subgenus  described  by  the  same 
author  from  the  Schwagerina  horizon  in  Russia. 

Spiriferina  zewanensis  Diener  (Plate  XIII,  Fig.  3) 

There  is  one  nearly  perfect  but  somewhat  compressed  specimen  (7312)  of 
a  species  of  Spiriferina  having  the  pedicle- valve  in  a  good  state  of  preserva¬ 
tion  and  not  crushed ;  the  brachial  valve  is  somewhat  flattened  by  pressure, 
but  it  shows  all  essential  characters,  and  the  ornamentation  of  the  surface 

67 Girty,  Bull.  544,  U.  S.  Geol.  Surv.,  1915,  p.  91,  PI.  XI,  Fig.  5. 

68  Tschernyschew,  op.  cit.,  p.  527,  t.  XL,  Figs.  1  to  4. 

69  Broili,  Palasont.  Timor,  VII,  No.  12,  1916,  p.  34,  t.  CXIX,  Figs.  1  to  11,  t.  CXX, 
Figs.  1  to  6. 

60  Tschernyschew,  op.  cit.,  p.  569,  t.  L,  Figs.  1  to  3. 

61  Mansuy,  op.  cit.,  vol.  V,  fasc.  4,  1916,  p.  33,  PL  V,  Fig.  10. 

62  Tschernyschew,  op.  cit.,  p.  557,  t.  L,  Fig.  4. 


140  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

of  both  valves  is  beautifully  preserved.  In  the  pedicle-valve  there  are  four 
(and  a  weaker  fifth)  strong  angular  folds  on  each  side  of  the  median  sinus, 
which  is  broad,  subangular,  and  rather  rapidly  increases  in  width  anteriorly ; 
the  pair  of  folds  bordering  it  are  the  strongest  of  the  series,  the  others  suc¬ 
cessively  decreasing  in  size  toward  the  cardinal  region,  a  smooth  triangular 
space  devoid  of  ribs  being  left  along  the  cardinal  line.  The  beak  is  small, 
acute,  elevated  and  slightly  incurved,  but  not  high,  and  the  hinge-area  is 
low  and  narrow.  The  brachial  valve  has  a  narrow,  prominent  median  fold, 
rounded  rather  than  subangular  and  very  slowly  increasing  in  width  anteri¬ 
orly  ;  there  are  only  three  strong  subangular  folds  on  each  side  and  traces  of 
a  fourth  one.  The  cardinal  angles  of  both  valves  are  broken  off,  but  seem  to 
have  been  acute  or  subacute.  The  surface  of  both  valves  is  covered  with  a 
series  of  strong,  equidistant,  regular,  thick  imbricating  lamellae  about  twenty 
to  twenty-five  in  number,  and  the  shell  substance  is  coarsely  punctate.  A 
very  delicate  radial  striation  is  also  visible  with  a  lens  on  the  surface. 

Dimensions — Length,  14  mm.;  width  (estim.),  28  mm. 

Remarks — This  shell  is  much  like  Sp.  octoplicata  Sow.  as  redefined 
by  North,  especially  the  mut.  8  Vaughan,63  but  the  species  from  the  Zewan 
beds  of  Kashmir  which  Diener64  first  described  as  Sp.  cf.  kentuckiensis 
Shum.,  but  subsequently  as  Sp.  zewanensis  sp.  nov.,  seems  to  be  indistin¬ 
guishable  from  our  specimen. 

Reticularia  notica  sp.  nov.  (PI.  XIII,  Figs.  8a,  8b,  10) 

Shell  subcircular.  Pedicle  valve  moderately  convex;  beak  high,  promi¬ 
nent,  pointed,  incurved,  with  umbonal  slopes  hollow;  cardinal  area  concave, 
triangular,  steeply  inclined;  hinge-line  short,  about  half  width  of  shell.  Sur¬ 
face  of  valve  marked  with  continuous  median  shallow  sinus,  scarcely  increas¬ 
ing  in  width  anteriorly.  Ornamentation  of  shell  consisting  of  numerous 
closely  placed  subequidistant  concentric  thin  lamellae  with  their  edges  pro¬ 
vided  with  minute  equidistant,  rather  widely  spaced,  small,  short,  simple, 
recumbent  spines,  not  crossing  the  lamellae  but  forming  narrow  fringes. 
Brachial  valve  unknown. 

Dimensions — Length,  15  to  16  mm.;  width,  14  to  15  mm. 

Remarks — This  species,  of  which  there  is  one  broken  example  (7326)  of 
a  pedicle  valve  having  the  surface  beautifully  preserved  and  showing  the 
ornamentation,  and  three  other  decorticated  and  poor  specimens  (7376, 
7345,  7372)  can  not  be  referred  to  Ret.  lineata  Mart.,  because  of  the  median 
sinus  and  the  character  of  the  marginal  spinose  fringes.  But  as  often  remarked, 
R.  lineata  has  been  made  to  include  a  variety  of  forms.  It  is  more  like  Ret . 
setigera  Hall  and  Whitfield 65  in  the  ornamentation  and  in  the  median  sinus 
and  shape  we  may  also  compare  R.  orientalis  Mansuy,66  and  Ret.  rostrata 
Kut.67  R.  waageni  Loczy,68  from  southern  China  and  especially  Squamularia 
guadelupensis  Shum.69  from  Texas,  may  also  be  compared. 

63  North,  Quart.  Journ.  Geol.  Soc.,  vol.  LXXVI,  pt.  2,  1920,  p.  217,  PI.  XIII,  Fig.  9. 

64  Diener,  Himal.  Foss.,  vol.  I,  pt.  2,  1899,  p.  61,  PI.  V,  Figs.  11  and  12;  id.  Anthrac. 
Foss.  Kashmir,  etc.  (Palasont.  Ind.,  vol.  VI,  mem.  2,  1915),  p.  90,  PI.  IX,  Fig.  12. 

65  Hall  and  Whitfield,  Explor.  40th  Parallel,  p.  270,  PI.  VI,  Figs.  17  and  18. 

66  Mansuy,  op.  oil.,  vol.  II,  fasc.  4,  p.  81,  PI.  IX,  Fig.  2. 

67  Tschernyschew,  op.  cit.,  p.  575,  t.  XX,  Figs.  14  to  18. 

68  Loczy,  Beschr.  Wiss.  Ergeb.  Pal.  Stratigr.  Result.  Reise  des  Grafen  Bela  Szechenyi. 
(Budapest,  1898),  p.  no,  t.  IV,  Figs.  1  and  2. 

69Girty,  op.  cit.,  1908,  pp.  367  to  369,  PI.  XIV,  Figs.  2  and  3. 


UPPER  CARBONIFEROUS  FOSSILS  FROM  ARGENTINA 


141 


Ambocoelia  plano-convexa  Shumard 

This  well-known  brachiopod,  which  occurs  in  the  upper  Carboniferous 
of  America,70  Asia,71  and  Europe72  and  was  recorded  by  Derby73  from  the 
coal  measures  of  Brazil  and  by  Kozlowski74  from  the  upper  Carboniferous  of 
Bolivia,  is  represented  by  one  pedicle-valve  in  the  collection,  measuring 
about  7.5  mm.  in  width  and  about  5  mm.  in  length. 

Athyris  ( Spirigerella )  ?  sp. 

There  is  one  fragmentary  specimen  of  a  broadly  subcircular  pedicle- 
valve  with  a  weak  anterior,  broad,  median  sinus,  and  strong  concentric 
growth-ridges  which  seems  to  belong  to  some  species  of  Athyris  or  Seminula 
and  may  perhaps  be  compared  with  Spirigerella  grandis  Waag.75  and  the 
allied  species  from  the  Productus  limestones.  We  may  also  compare  some  of 
the  shells  from  the  upper  Carboniferous  of  Bolivia  figured  by  Kozlowski76 
under  the  name  Seminula  argentea  (Shepard) ,  for  the  genus  of  our  specimen 
is  uncertain. 


Hemiptychina  cf.  sublx vis  Waagen  (Plate  XIII,  Fig.  5) 

A  small  oval  terebratuloid  shell  (7300  showing  only  the  pedicle- valve 
has  the  external  appearance  and  shape  of  Hemiptychina  sublcevis  Waag.,77 
but  its  identification  is  somewhat  uncertain.  It  measures  about  6.5  mm. 
in  length. 

Pseudamusium  stappenbecki  sp.  nov.  (Plate  XIII,  Figs.  11  and  13) 

Shell  obliquely  subelliptical,  longer  than  high,  transverse,  bilaterally 
asymmetrical,  having  an  oblique  axis  and  anterior  swing;  gently  biconvex, 
compressed.  Right  valve  with  body  gently  convex,  more  or  less  flattened; 
beak  pointed,  with  its  edges  meeting  at  a  right  angle  or  more  than  a  right 
angle,  situated  excentrally  at  about  one-third  the  length  of  the  valve  from 
posterior  end;  anterior  end  of  valve  rounded,  projecting  in  front,  strongly 
arched  forward  above,  curving  back  sharply  below  into  inferior  margin,  which 
makes  a  wider,  gentler  curve  and  passes  obliquely  up  into  shorter,  more 
semicircular  posterior  margin;  junction  of  body  above  with  posterior  ear 
straight ;  junction  of  body  with  anterior  ear  slightly  concave.  Anterior  ear 
large,  narrow,  long,  acutely  triangular,  depressed,  sharply  marked  off  from 
body,  rounded  in  front,  without  byssal  slit;  surface  marked  with  four  to  five 
broad,  low  radial  folds.  Posterior  ear  small,  short,  depressed,  smooth,  weakly 
but  distinctly  marked  off  from  body,  with  obtuse  posterior  angle,  higher 
than  long,  extending  a  short  distance  down  posterior  margin  of  body. 
Surface  of  body  marked  with  very  faint,  low,  wide,  flattened  radial  ribs 
of  subsequal  size,  separated  by  incised  lines  and  only  distinct  toward  the 
margins;  a  few  closely  placed  fine  raised  radial  lines  are  present  on  anterior 
and  posterior  upper  margins  of  body  near  junctions  with  ears;  strong  con¬ 
centric  stride  and  growth-ridges  at  unequal  distances  apart  cover  the  whole 
surface  of  both  valves.  Left  valve  similar  to  right  valve,  but  with  the  fine 
radial  lines  extending  over  more  of  the  surface  of  the  body. 

Dimensions — Length  (oblique),  25  mm.;  height,  22  mm. 

70  Girty,  Bull.  544  U.  S.  Geol.  Surv.  1915,  p.  94  and  refs. 

71  Mansuy,  op.  cit.,  vol.  II,  fasc.  4,  1913,  p.  82,  PI.  IX,  Fig.  4. 

72  Tschemyschew,  op.  cit.,  p.  575,  t.  XX,  Fig.  1. 

73  Derby,  Bull.  Cornell  Univ.,  1874,  p.  19,  PI.  VIII,  Figs.  12,  16,  18,  PI.  IX,  Fig.  7. 

74  Kozlowski,  op.  cit.,  1914,  p.  76,  Text-Fig.  19,  PI.  I,  Fig.  5,  PI.  X,  Figs.  1  to  14. 

75  Waagen,  op.  cit.,  p.  461,  PI.  XXVI,  Figs.  1  to  7  (especially  Figs.  3  and  4). 

76  Kozlowski,  op.  cit.,  1914,  p.  79,  PI.  XI,  Figs.  1  to  46. 

77  Waagen,  op.  cit.,  p.  364,  PI.  XXVII,  Figs.  1  to  3;  Diener,  Palasont.  Ind.,  ser.  XV, 
Vol.  I,  PI.  V,  1903,  p.  40,  PI.  II,  Figs.  3  a  to  d. 


142  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

Remarks — This  species  is  represented  by  several  fairly  perfect  speci¬ 
mens,  but  the  radial  ribbing  is  only  seen  in  those  having  the  shell  more  or 
less  preserved,  most  of  the  specimens  being  casts  in  which  the  concentric 
lines  and  ridges  are  more  conspicuous. 

The  right  valves  (7287,  7290,  7303)  are  more  complete  than  any  of  the 
left  valves  (7301?,  7302,  7291,  7289,  7284),  but  there  seems  to  be  little  or  no 
difference  in  their  characters.  The  generic  reference  of  this  shell  is  to 
Pseudamusium  as  defined  by  Wheelton  Hind,  and  it  seems  allied  especially 
to  Ps.  anisotum  Phill.78  and  to  Pecten  sibiricus  De  Vern.,79  which  Hind  con¬ 
siders  to  be  probably  identical. 

Diener80  has  figured  an  unnamed  species  of  t(  Aviculo  pecten”  from  the 
Zewan  beds  which  seems  rather  to  resemble  the  Argentine  shell.  The  well- 
known  Russian  species  Av.  sericeus  De  Vern.81  is  less  oblique  and  less  trans¬ 
verse,  and  the  same  differences  are  noticeable  in  the  Amazonian  upper 
Carboniferous  shell  which  Katzer82  has  figured  as  Euchondria  neglecta 
Geinitz.  But  Herrick’s  species  Crenipecten  foerstiizz  of  the  Pottsville  fauna 
closely  resembles  our  species  in  character. 

Pseudamusium  cf.  ellipticum  (Phillips)  (Plate  XIII,  Fig.  12) 

There  seems  to  be  another  species  of  Pseudamusium  in  the  collection 
which  is  only  represented  by  one  good  example  of  a  left  valve  (7304),  and 
it  differs  from  the  foregoing  in  its  shape  and  apparently  in  its  ornamenta¬ 
tion.  It  is  not  oblique  and  is  higher  than  long,  being  a  bilaterally  symmetri¬ 
cal  oval  shell  like  a  Pecten;  the  sides  of  the  beak  which  is  central  in  position, 
meet  at  about  750;  the  anterior  ear  is  shorter  broader,  and  more  equilater- 
ally  triangular  than  in  Ps.  stappenbecki  and  shows  concentric  lines  instead  of 
radial  ribs.  The  long,  straight  shoulders  of  the  body  descend  nearly  to  the 
middle  of  the  valve.  The  surface  is  gently  convex,  and  though  the  shell  is 
mostly  missing,  there  is  a  regular  fine  radial  lineation  visible  over  the  whole 
surface,  passing  into  broad,  flattened  ribs  near  the  margins,  which  are  more 
distinct  than  in  the  previous  species,  and  the  concentric  ridges  and  striae 
are  less  well  developed. 

This  shell  seems  to  resemble  Ps.fibrillosum  (Salt.)  of  the  Coal  Measures 
of  England,  as  described  by  Wheelton  Hind,84  but  still  more  Ps.  ellipticum 
Phill.85  of  the  Carboniferous  limestone  of  Great  Britain  and  Ireland. 

Dimensions — (7304) :  Height,  25  mm.;  length,  19  mm. 

Pseudamusium  cf.  fibrillosum  (Salter) 

There  is  one  left  valve  (7324)  of  a  species  of  Pseudamusium  which  seems 
more  like  Ps.  fibrillosum  (Salt.)85  as  described  by  Wheelton  Hind  than 
Ps.  anisotum,  Ps.  ellipticum,  or  Ps.  redesdalense  Wh.  Hind.  It  has  the  up¬ 
right  oval  shape  and  vertical  axis  of  Ps.  ellipticum  and  Ps.  fibrillosum,  but 
the  finer  ornamentation  of  the  latter  without  any  wide,  flat  ribs. 

Aviculopecten  barrealensis  sp.  nov.  (Plate  XIII,  Fig.  14) 

Shell  obliquely  oval,  gently  convex.  Body  subtriangular,  rounded; 
beak  subanterior,  small,  with  sides  meeting  at  about  90°.  Anterior  margin 
of  shell  short,  strongly  arched,  sweeping  down  and  back  obliquely  into  well- 

78  Wheelton  Hind,  Brit.  Carb.  Lamellibr.,  vol.  II,  1903,  p.  104,  PI.  XXI,  Figs.  13  to  20. 

79  De  Verneuil,  Geol.  Russ.,  II,  Palaeont.,  p.  329,  PI.  XXI.  Fig.  7. 

80  Diener,  Himal.  Foss.,  vol.  I,  pt.  2,  1899  (Palseont.  Ind.),  p.  16,  PI.  I,  Fig.  3. 

81  Stuckenberg,  Mem.  Com.  Geol.  Russ.,  vol.  XVI,  no.  1,  1898,  p.  200,  t.  I,  Fig.  22. 

82  Katzer,  Grundziige  d.  Geol.  d.  unter.  Amazonasgebietes  (Leipzig,  1903),  p.  185, 
t.  VIII,  Fig.  6. 

83  Morningstar,  Geol.  Surv.  Ohio,  Ser.  4,  Bull.  25,  1922,  p.  230,  PI.  XIII,  Figs.  7,  8. 

84  Wheelton  Hind,  op.  cit.,  p.  106,  PI.  XVI,  Figs.  16  to  22. 

85 Ibid.,  p.  103,  PI.  XX,  Figs  n  to  18. 


UPPER  CARBONIFEROUS  FOSSILS  FROM  ARGENTINA 


143 


arched  inferior  margin  which  curves  up  sharply  behind  with  short  rounded 
projecting  posterior  end.  Ears  well  marked  off  from  body,  flattened 
depressed;  anterior  ear  rather  large,  triangular,  projecting,  with  rounded 
anterior  margin ;  [posterior  ear  larger  ( ?) ,  triangular,  with  acute  ( ?)  posterior 
angle].  Surface  of  valve  covered  with  fine,  regular,  straight,  mostly  equi¬ 
distant,  threadlike,  raised  radiating  ribs,  of  equal  strength,  thirty  to  thirty- 
three  in  number,  less  than  half  being  primary  and  continuous  from  beak  to 
margin,  the  rest  arising  by  intercalation  mostly  at  about  one-fourth  the 
length  of  the  others;  interspaces  wide,  flat,  all  of  them  as  well  as  the  ribs 
being  crossed  by  rather  closer,  finer,  regular,  threadlike  raised  lines  which 
are  equidistant  in  the  lower  half  of  the  shell,  but  become  more  and  more 
crowded  and  numerous  toward  the  beak.  Anterior  ear  with  concentric 
growth-lines. 

Dimensions — (7362):  Length  (oblique),  11.5  mm.;  height,  9.0  mm. 

Remarks — Only  one  specimen  (7362)  occurs  in  the  collection,  but  it  is 
a  nearly  perfect  left  valve.  The  surface  of  this  shell  is  divided  up  into 
numerous  oblong  cancellce  by  the  crossing  of  the  radial  and  concentric 
lines,  as  in  A.forbesii  McCoy,86  which  it  also  much  resembles  in  shape,  but 
this  Argentine  species  differs  by  the  ribs  being  of  equal  strength,  and  the 
obliquity  of  the  shell  is  more  marked  and  the  body  narrower  and  not  subor- 
bicular.  Ps.  radialis  (Phill.)  as  figured  by  Waagen87  from  the  Salt  Range 
has  a  somewhat  similar  ornamentation. 

Nuculana  ( Leda )  cf.  bellistriata  Stevens  (Plate  XIII,  Fig.  7) 

One  small  right  valve  of  a  species  of  Nuculana  occurs  in  the  collection 
(7339)*  but  it  is  only  an  internal  cast  and  does  not  show  the  dentition.  It 
seems  somewhat  like  N.  bellistriata  Stevens,88  from  the  Pennsylvanian  of 
the  United  States,  but  is  shorter  and  blunter  behind.  Probably  it  is  a 
new  species. 

Dimensions — Length,  10  mm.;  height,  7  mm. 

Euomphalus  subcircutaris  Mansuy  (Plate  XV,  Figs.  1,2,4) 

There  is  a  species  of  Euomphalus  rather  abundantly  represented  in  the 
collection  and  including  several  well-preserved  specimens  which  seems 
absolutely  indistinguishable  from  Mansuy’s  E.  subcircularis 89  from  the 
Carboniferous  of  Chouei  Tang,  Yunnan.  Apparently  this  is  the  shell  which 
Stappenbeck  mentions  from  Barreal  as  resembling  E.  parvus  Waag.,90  but 
as  being  much  larger. 

The  specimens  average  about  25  to  30  mm.  in  diameter,  and  some 
of  them  (7322)  are  well  preserved  and  show  both  the  apical  and  basal  sur¬ 
faces.  In  all  respects  they  agree  with  Mansuy’s  figures  and  description, 
which  need  not  be  repeated. 

Pleurotomaria  ad  vena  sp.  nov.  (Plate  XV,  Fig.  5) 

Shell  low,  conical,  heliciform,  height  and  diameter  being  about  equal, 
basal  whorl  occupying  about  half  the  height;  apical  angle  about  130°; 
whorls  rounded,  five  to  six  in  number,  rapidly  decreasing  in  size  to  apex. 
Basal  whorl  large,  rounded  below,  more  or  less  flattened  above,  rising  at 
an  angle  of  450  to  6o°  from  the  periphery,  which  is  obtuse;  slit-band  promi- 

86  Wheelton  Hind,  op.  cit.,  p.  83,  PI.  XVIII,  Figs.  3  to  7. 

87  Waagen,  op.  cit.,  p.  280,  PI.  XXIII,  Fig.  5. 

88 Girty,  Bull.  544,  U.  S.Geol.  Surv.,  1915,  p.  122,  PI.  XIV,  Figs.  1  to  9;  Jakowlew, 
Mem.  Com.  Geol.  Russ.,  n.s.,  Livr.  4,  1903,  p.  10. 

89  Mansuy,  op.  cit.,  vol.  I,  fasc.  2,  1912,  p.  105,  PI.  XIX,  Figs.  3a  to  d. 

90  Waagen,  op.  cit.,  p.  89,  pi.  IX,  Fig.  2. 


144  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

nent,  situated  slightly  above  the  periphery,  narrow,  concave,  deep,  with 
sharp  raised  edges.  Upper  whorls  rounded.  Sutures  not  deeply  sunken, 
with  slit-band  on  upper  whorls  situated  on  or  slightly  above  them.  Base  of 
shell  convex,  rounded;  umbilicus  small,  closed,  depressed;  lip  of  mouth 
somewhat  thickened.  Shell  ornamented  with  revolving  liras  crossed  by  finer 
spiral  lines  which  at  their  intersection  form  small  pustules  or  nodules  giving 
a  moniliform  character  to  the  lirae;  on  apical  surface  of  each  whorl  above  the 
slit-band  there  are  five  to  seven  of  such  equidistant  revolving  liras  of  equal 
strength,  closely  nodulated,  mostly  with  finer,  similarly  nodulated  liras 
between  them;  below  the  slit-band  on  the  basal  whorl  are  more  numerous 
and  more  closely  placed  finer  nodulated  liras,  with  the  closely  placed  spiral 
lines  bending  back  to  meet  the  slit-band  at  an  angle  of  about  20°. 

Dimensions — Height,  c.  30  mm. ;  basal  diameter,  c.  35  mm. 

Remarks — There  is  one  specimen  (7355)  somewhat  crushed  but  showing- 
well  the  basal  whorl,  slit-band,  and  ornamentation.  Another  (7360)  shows 
the  spire  and  upper  whorls  better.  The  species  seems  to  be  allied  to  PL 
punjabica  Waag.91  of  the  upper  Productus  limestone  of  the  Salt  Range, 
but  differs  in  the  upper  whorls  being  more  rounded,  in  the  slit-band  being 
sutural,  and  in  the  more  marked  nodulation  of  the  revolving  liras.  We  may 
perhaps  also  compare  PI.  timorensis  Wanner92  from  the  Permo-Carbonifer¬ 
ous  of  Timor  and  Ptychomphalus  venustus  Mansuy93  from  the  correspond¬ 
ing  beds  of  Indo-China,  especially  with  regard  to  the  shape  of  the  shell  and 
its  ornamentation. 

Pleurotomaria  argentina  sp.  nov.  (Plate  XV,  Figs.  3a,  3 b,  3c) 

Shell  conical,  subtrochiform ;  apical  angle  750;  whorls  five  to  six  in 
number,  bluntly  angulated  at  periphery,  slowly  decreasing  in  size.  Basal 
whorl  large,  fully  half  the  total  height  of  the  shell,  with  swollen,  convex 
rounded  base,  subangular  periphery  bearing  a  prominent,  well-defined, 
sunken,  narrow  slit-band  having  sharply  raised  edges,  and  with  a  somewhat 
flattened  apical  face  sloping  up  to  suture-line.  Upper  whorls  with  promi¬ 
nent  suture-band  situated  a  little  distance  above  suture-line,  which  is  not 
sunken.  Surface  of  whorls  marked  with  regular  revolving  lirae,  numbering 
six  to  seven  on  apical  face,  equidistant  and  bearing  regular  sharp,  equi¬ 
distant,  small  spinose  tubercles;  below  the  slit-band  on  the  upper  whorls 
are  one  to  three  similar  lirae.  Lower  surface  of  basal  whorl  with  several 
similar  equidistant  lirae  immediately  below  slit-band,  but  nearer  umbilicus 
they  become  finer  and  less  distinct  or  obsolete,  fine  spiral  growth-lines 
being  here  specially  developed.  Umbilicus  sunken,  closed.  Mouth  large, 
subcircular. 

Dimensions — (7334) :  Height,  c.  27  mm.;  diameter,  c.  24  mm. 

Remarks - — This  species  is  closely  allied  to  PI.  ( Phanerotrema )  gray - 
villensis  Norvv.  and  Pratt,  as  described  by  Girty 94  from  the  Pennsylvanian  of 
Oklahoma,  differing  chiefly  in  the  absence  of  strong  spiral  lines  crossing  the 
revolving  lirae,  and  of  the  transverse  ridges  below  the  suture-lines  on  the 
apical  surface  of  the  whorls. 

Pleurotomaria  barrealensis  sp.  nov.  (Plate  XVI,  Figs.  in,  16) 

Shell  subturbinate,  composed  of  four  to  five  rounded  whorls,  rather 
rapidly  decreasing  in  size  to  apex;  apical  angle  about  8o°.  Basal  whorl 

91  Waagen,  op.  cit.,  p.  115,  PI.  XI,  Figs.  3  and  4. 

92  Wanner,  Palaeont.  Timor,  Lief.  XI,  Abh.  XVIII,  1922,  p.  20,  t.  151,  Figs.  9 a  and  6. 

93  Mansuy,  op.  cit.,  vol.  II,  fasc.  4,  1913,  p.  102,  PI.  XI,  Fig.  3. 

94 Girty,  Bull.  544  U.  S.  Geol.  Surv.,  1915,  p.  149,  PI.  XXIII,  Figs.  2  to  8. 


UPPER  CARBONIFEROUS  FOSSILS  FROM  ARGENTINA 


145 


large,  rounded-subquadrate  in  section,  being  somewhat  flattened  on  outer 
face;  slit-band  narrow,  inconspicuous,  situated  at  junction  of  outer  face 
with  convex  apical  face;  inferior  surface  of  basal  whorl  rounded,  but  not 
strongly  convex,  somewhat  flattened;  umbilicus  sunken,  small;  mouth 
transversely  oval,  wider  than  high,  with  thickened  inner  lip.  Upper  whorls 
with  more  or  less  flattened  vertical  outer  face  below  the  slit-band,  which  is 
situated  in  about  the  middle  of  each  whorl.  Inferior  surface  of  basal  whorl 
crossed  by  strong  subequidistant,  sublamellose,  spiral  growth-lines  and  by 
numerous  rather  closely  placed,  subequidistant,  thick,  thread-like,  smooth 
revolving  liras,  not  tuberculated;  outer  face  of  basal  whorl  ornamented  with 
similar  more  widely  spaced  revolving  liras;  apical  face  (not  well  preserved) 
ornamented  with  similar  revolving  liras. 

Dimensions — Height,  c.  55  mm.;  diameter  at  base,  c.  55  mm. 

Remarks — There  is  only  one  specimen  (7323)  of  this  shell,  but  it  is 
nearly  complete,  though  the  surface  ornamentation  is  destroyed,  except  on 
the  basal  whorl,  and  the  slit-band  is  nowhere  distinct.  We  may  compare  this 
species  with  PI.  orientalis  Roemer,  as  figured  by  Fliegel95  from  the  upper 
Carboniferous  of  Padang,  Sumatra,  and  with  PL  cf.  punjabica  Waag.  as 
figured  by  Diener 96  from  the  Productus  shales  of  the  Himalayas. 

Metoptoma  ?  sp. 

One  much-crushed  subcircular  shell  (7318)  may  possibly  be  referred  to 
the  genus  Metoptoma ,  for  apparently  it  had  a  low  capuliform  shape  with  an 
elevated  submarginal  apex  scarcely  overhanging  the  posterior  margin.  The 
surface  of  the  shell  seems  to  have  been  gently  convex,  very  obliquely  coni¬ 
cal,  and  there  are  traces  of  twx>  to  three  small,  short  marginal  radial  folds 
in  the  median  line  on  the  anterior  edge.  On  one  part  of  the  central  pre- 
umbonal  region  regular  fine,  equidistant,  incised  radial  lines  are  visible,  and 
a  few  concentric  growth-strias  and  ridges  sweep  around  the  margins  and  pass 
beneath  the  umbo. 

Dimensions — Diameter,  22  to  25  mm. ;  height,  +  4  mm. 

Orthoceras  sp. 

One  small  fragment  of  a  subcylindrical  shell  with  a  circular  cross-section 
is  probably  referable  to  a  species  of  Orthoceras.  The  specimen  is  only  10.5 
mm.  in  length  and  shows  five  to  six  horizontal  septa  in  that  distance.  The 
siphuncle  is  central  and  circular  and  measures  one-sixth  to  one-seventh  of 
the  diameter.  The  walls  of  the  cameras  seem  to  be  unusually  thick.  The 
external  surface  of  the  shell  seems  to  be  smooth,  except  for  very  delicate 
concentric  striae.  The  affinities  of  this  fragment  are  not  clearly  determinable, 
owing  to  the  poorness  of  the  specimen.  Another  fragment  (7354)  of  appar¬ 
ently  the  same  species  consists  of  one  broken,  isolated  camera;  the  septa 
are  seen  to  be  deeply  concave  and  the  siphuncle  apparently  expands  in  the 
upper  part  of  each  chamber.  If  the  thickness  of  the  walls  of  the  chambers 
as  seen  in  the  other  specimen  is  due  to  a  marginal  infilling  we  may  per¬ 
haps  compare  Pseudorthoceras  knoxense  Girty97  from  the  Pennsylvanian  of 
America,  which  also  agrees  in  its  slow  rate  of  tapering,  central  siphuncle, 
distance  apart  of  the  septa,  and  circular  section.  The  rate  of  tapering, 
central  siphuncle,  circular  section,  and  distance  apart  of  the  septa  in  our 
specimens  also  suggest  a  comparison  with  Orth,  punjabiense  Waag.98  from 
the  middle  Productus  limestone  of  Musakheyl. 

95  Fliegel,  Palaeontographica,  Bd.  XLVIII,  Lief.  3,  1901,  p.  113,  t.  VIII.  Figs.  7  and  8. 

96  Diener,  Palaeont.  Ind.,  ser.  XV,  Vol.  I,  pt.  5,  1903,  p.  100,  PI.  V,  Figs.  1  to  3. 

97  Girty,  Bull.  544  U.  S.  Geol.  Surv..  p.  227,  PI.  XXVII,  Figs.  1  to  6 

98Waagen,  op.  cit p.  71,  PI.  VI.  Fig.  11. 


146  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 


COMPOSITION  AND  CORRELATION  OF  THE  FAUNA 

The  following  is  a  list  of  the  species  in  the  present  collection 
which  have  been  identified  and  described  above : 

*  Fenestella  aft.  perelegans  Meek. 

sp.  ind. 

Polypora  aff.  biseriata  Ulr. 

Orbiculoidea  saltensis  sp.  nov. 

*t Productus  lineatus  Waag. 

*  curvirostris  Schellw.  var.  nov.  barrealensis. 

*  cf.  juresanensis  Tschern. 

*  ( Marginifera )  cf.  echinata  Waag. 

*  ( Marginifera )  spinulo-co status  Abich  var.  nov.  peregrina. 

*Chonetes  cf.  pseudovariolata  Nik. 

granulifer  Owen. 

*Camarophoria  cf.  mutabilis  Tschern. 

*Spirifer  cf.  supramosquensis  Nik. 

*  wynnei  Waag.  var.  nov.  argentina. 
saltensis  sp.  nov. 

barrealensis  sp.  nov. 

mexicanus  Shum.  var.  nov.  neotropica. 

*  aff.  rajah  Salt. 

*  (Martini a)  cf.  simensis  Tschern. 

*  ( Martiniopsis )  cf.  aschensis  Tschern. 

* Spiriferina  zewanensis  Diener. 

Reticular ia  notica  sp.  nov. 

*\Ambocoelia  plano-convexa  Shum. 

Athyris  ( Spirigerella )  ?  sp. 

*Hemipty china  cf.  sublcevis  Waag. 

Pseudamusium  stappenbecki  sp.  nov. 

cf.  ellipticum  (Phill.). 
cf.  fibrillosum  (Salt.). 

Aviculopecten  barrealensis  sp.  nov. 

Nuculana  ( Leda )  cf.  bellistriata  Stevens. 

Euomphalus  subcircularis  Mansuy. 

Pleurotomaria  advena  sp.  nov. 

argentina  sp.  nov. 
barrealensis  sp.  nov. 

Metoptoma  ?  sp. 

Orthoceras  sp. 

With  regard  to  the  two  horizons  in  the  shales  from  which  Doctor 
Du  Toit’s  specimens  were  collected  the  following  lists  indicate  the 
distribution  of  the  species : 

Lower  horizon  (7281-7313). 

Polypora  aff.  biseriata. 

Fenestella  sp.  ind. 

Productus  cl.  juresanensis. 

Spirifer  wynnei  var.  argentina. 
saltensis. 

Spiriferina  zewanensis. 

Hemipty china  cf.  sublcevis. 

Pseudamusium  stappenbecki. 

cf.  ellipticum. 


UPPER  CARBONIFEROUS  FOSSILS  FROM  ARGENTINA 


147 


Upper  horizon  (7314-7376). 

Fenestella  aff .  perelegans. 

Orbiculoidea  saltensis. 

Productus  lineatus. 

curvirostris  var.  barrealensis. 

( Marginifera )  cf.  echinata. 

( Marginifera )  spinulo-co status  var.  peregrina. 

Chonetes  cf.  pseudovariolata. 
granulifer  Owen. 

Camarophoria  cf .  mulabilis. 

Spirifer  cf.  supramosquensis. 
barrealensis. 

mexicanus  var.  neotropica. 

{Martinia)  cf.  simensis. 

( Martinia )  cf.  aschensis. 

Reticularia  notica. 

Pseudamusium  cf.fibrillosum. 

Aviculopecten  barrealensis. 

Nuculana  cf.  bellistriata. 

Euomphalus  sub  circular  is. 

Pleurotomaria  advena. 

argentina. 

barrealensis. 

Metoptoma  ?  sp. 

Orthoceras  sp. 

The  species  marked  with  an  asterisk  (*)  in  the  above  list  occur 
either  in  the  Carboniferous  of  Russia  or  parts  of  Asia,  though  several 
are  represented  here  by  varieties.  In  many  cases  we  have  not  been 
able  to  feel  sure  that  the  other  species  are  identical,  owing  to  the 
paucity  or  poor  preservation  of  the  specimens  in  the  present  col¬ 
lection,  so  that  they  can  only  be  compared  with  already  described 
forms.  A  few  are,  however,  identified  without  hesitation;  such  are 
Productus  lineatus ,  Chonetes  granulifer,  Amboccelia  planoconvexa,  Spiri- 
jerina  zewanensis,  and  Euomphalus  sub  circular  is. 

The  species  marked  with  a  dagger  (f)  have  been  recorded  by 
previous  geologists  from  South  America,  but  these  are  very  few,  and 
the  remainder  show  little  affinity.  The  fauna,  in  fact,  of  this  Argen¬ 
tine  locality  is  quite  distinct  from  that  of  Brazil  or  Bolivia,  and  does 
not  show  any  striking  resemblance  to  any  occurring  in  North 
America,  except  perhaps  to  the  Guadelupian  type. 

Derby,"  in  1894,  gave  a  list  of  the  Amazonian  upper  Carbonifer¬ 
ous  fauna,  but  without  any  figures  or  descriptions.  Many  had  been 
described  in  his  earlier  paper  on  the  Brazilian  Carboniferous  fossils 
from  Itaituba.  The  most  complete  list  of  the  upper  Carboniferous 
fossils  from  the  Amazon  region,  with  descriptions  and  figures  of 
several  of  the  species,  was  given  by  Katzer,100  in  1903.  Among  the 
species  occurring  in  this  area  and  the  present  collection  from  Barreal 

99  Derby,  Journal  of  Geology,  vol.  II,  1894,  p.  480. 

100  Katzer,  Grundzuge  d.  Geol.  d.  unter  Amazonasgebietes  (Leipzig,  1903),  pp.  142- 
188,  263-268,  t.  IV-VIII. 


148  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 

are:  Productus  lineatus  and  Amboccelia  plano-convexa,  while  probably 
some  of  the  shells  referred  to  Sp.  condor  by  Katzer  ( e.g .,  op.  cit.,  t. 
V,  Fig.  i)  should  be  identified  with  Sp.  ef.  supramosquensis ,  and  Pr. 
nebraskensis  may  be  the  same  as  the  shell  compared  with  Pr.  juresa- 
nensis.  But  the  Amazonian  fauna,  which  is  a  large  one,  consists 
mainly  of  species  not  recognized  at  Barreal.  Katzer  (op.  cit., 
pp.  246-253)  has  discussed  the  relations  of  this  fauna  with  that  of 
other  regions  and  has  referred  to  the  literature  on  the  subject. 

The  relations  of  the  Argentine  fauna  to  that  of  the  upper  Car¬ 
boniferous  of  Bolivia,  of  which  the  brachiopods  alone  have  been 
adequately  studied,  is  not  close,  as  is  seen  by  Kozlowski’s101  memoir. 
But  Amboccelia  plano-convexa  and  Productus  lineatus  (  =  cora  (pars) 
Kozl.)  are  species  which  the  two  faunas  have  in  common. 

Meyer,102  in  1914,  described  marine  upper  Carboniferous  faunas 
from  Peru  and  Bolivia  and  discussed  their  occurrence  generally  in 
South  America,  referring  to  Stappenbeck’s  discovery  of  such  at 
Barreal,  but  without  giving  any  further  particulars.  Of  the  Argen¬ 
tine  species,  Productus  cora  (including  Pr.  lineatus )  alone  is  men¬ 
tioned  as  occurring  in  Bolivia,  but  in  Peru  we  note,  in  addition  to  this 
species,  Amboccelia  plano-convexa.  Reviewing  the  evidence,  Meyer 
assigns  all  the  faunas  to  the  upper  Carboniferous  and  not  to  the 
Permian.  Douglas103  in  1914  briefly  described  a  similar  fauna  of  the 
Titicaca  district,  ascribing  it  to  the  upper  Carboniferous  or  Permo- 
Carboniferous,  and  he  recognized  that  a  few  forms  were  related 
to  “Permian”  forms  from  the  Salt  Range.  None  of  the  Argentine 
species  appear  to  occur.  In  a  subsequent  paper104  he  records  the 
occurrence  of  lower  Carboniferous  fossiliferous  beds  in  southern 
Peru,  but  the  fauna  is  quite  distinct  from  that  of  Barreal. 

There  is  not  any  very  close  resemblance  with  the  fauna  of  any 
part  of  the  Productus  limestones  of  Asia,  though  a  few  species  are 
apparently  identical  and  several  are  allied  or  comparable.  Hayasaka,105 
however,  has  described  a  small  fauna  of  brachiopods  from  the 
upper  Carboniferous  of  the  coal-bearing  series  of  Hon-kei-ko, 
Manchuria,  which  includes  the  following  species  occurring  at 
Barreal:  Camarophoria  cf.  mutabilis,  Spirifer  supramosquensis ,  Sp. 
wynnei,  and  some  other  allied  species  of  Spirifer. 

If  we  accept  Holland’s  correlation  of  the  Productus  limestones 106 
we  only  find  Spiriferina  zewanensis  of  the  Zewan  beds  as  a  Permian 
form,  though  Pleurotomaria  advena  is  more  allied  to  an  upper  Produc- 

101  Kozlowski,  Brach.  Carb.  Super.  Bolivie,  Annales  de  Paleont.  IX,  1914,  pp.  1  to  100 
Pis.  I  to  XI. 

102  Meyer,  Neues  Jahrb.  f.  Mineral,  etc.,  Beil.  Bd.  XXXVII,  1914,  pp.  590-651, 
t  XIII  XIV 

103  Douglas,  Quart.  Journ.  Geol.  Soc.,  vol.  LXX,  1914,  pp.  30-37,  Pis.  VIII,  IX. 

1MIbid.,  vol.  LXXVI,  1920,  p.  41. 

105  Hayasaka,  op.  cit.,  1922,  pp.  1 17-137. 

106  Holland,  Mem.  Geol.  Surv.  India,  vol.  LI,  pt.  1,  1926,  p.  22. 


UPPER  CARBONIFEROUS  FOSSILS  FROM  ARGENTINA 


149 


tus  limestone  species  than  to  any  other.  Productus  lineatus  and 
Amboccelia  planoconvexa,  though  occurring  in  the  Zewan  beds,  are 
abundant  also  on  lower  horizons  and  in  the  so-called  upper  Carbonif¬ 
erous  of  Russia  and  America.  Chonetes  granulifer  is  typically  a 
Pennsylvanian  species ;  and  the  species  Sp.  supramosquensis  is  char¬ 
acteristic  of  the  Gshelian,  which  occurs  immediately  above  the 
Moscovian  and  is  therefore  well  below  the  Permian.  If  we  look  at 
the  rest  of  the  species  from  Barreal,  we  observe  that  nearly  all  are 
closely  allied  to  or  comparable  with  established  species  from  either 
the  lower  Carboniferous  of  Europe  or  the  middle  or  upper  Car¬ 
boniferous  of  Russia  or  North  America,  and  that  none  are  limited 
to  undisputed  Permian  beds.  Thus  among  the  new  forms,  Spirifer 
saltensis  shows  close  affinities  with  some  examples  of  Sp.  duplicicosta 
of  the  lower  Carboniferous;  Sp.  barrealensis  is  especially  allied 
to  Sp.  boonensis;  Reticularia  notica  is  related  to  R.  setigera  of  the 
lower  Carboniferous ;  Pseudamusium  stappenbecki  has  affinities  with 
upper  Carboniferous  species ;  Pleurotomaria  argentina  closely  resem¬ 
bles  a  species  from  the  Pennsylvanian  of  the  United  States,  and 
PI.  barrealensis  is  like  an  upper  Carboniferous  form  from  Sumatra. 

Thus  the  weight  of  evidence  from  the  fossils  leads  us  without 
hesitation  to  refer  this  fauna  from  Barreal  to  the  Carboniferous ,  and 
it  seems  that  it  should  not  be  placed  at  the  top  of  that  formation,  but 
probably  toward  the  base  of  the  upper  division.  It  is  interesting  to  note 
that  Holland  (op.  cit.)  places  the  glacial  boulder  bed  of  the  Salt 
Range  in  the  Carboniferous,  for  the  tillite  of  Barreal  is  stated  to  pass 
up  into  and  even  include  some  of  the  beds  from  which  the  present 
collection  of  fossils  was  obtained. 


150  GEOLOGICAL  COMPARISON  OF  SOUTH  AMERICA  WITH  SOUTH  AFRICA 


TRIASSIC  FOSSILS  FROM  RIO  CLARO,  PARANA,  BRAZIL 

The  following  species  have  been  determined  provisionally  from  the 
material  forwarded  by  Doctor  Du  Toit,  but  it  is  intended  to  publish  full 
descriptions  and  figures  elsewhere  at  some  later  date.  The  fossils  from 
the  upper  zone  have  presented  difficulties  in  their  identification  owing  to 
their  occurrence  in  the  form  of  casts. 

Lower  Horizon — Zone  i  : 

Pachycardia  aff.  rugosa  Hauer. 

Anodontophora  aff.  trapezoidalis  Mansuy. 

Trigonodus  aff.  rablensis  (Gredler). 

Radiolaria  (not  determinable). 

Upper  Horizon — Zone  2: 

P achy  car  dia  neotropica  sp.  nov. 

Myophoria  ( Myophoriopis )  aff.  carinata  Bittn. 

aff.  lineata  Miinst. 

Megalodus  ?  neolropicus  sp.  nov.  cf.  triqueter  (Wulf). 

Gonodon  ( Schafhautlia )  paranaense  sp.  nov. 

Modiola  aff.  subcarinata  Bittn. 

Solenomorpha  in  the  sense  used  by  Holdhaus  is  not  represented  in  the 
collection,  nor  are  there  any  species  common  to  the  two  zones.  Permian 
forms  are  absent,  the  fossils  from  both  horizons  displaying  undoubted 
Triassic  characters  suggestive  of  the  upper  rather  than  the  lower  Trias. 


INDEX 


Authorities  Cited  in  the  Text 


Aguirre,  19,  21 

Arocena,  3,  4 

Ave-Lallemant,  4 7,  48 

Baker,  C.  L.,  61,  83,  87,  89,  90,  92-93 

Baker,  H.  A.,  11,  26 

Beder,  60,  77 

Berry,  40,  55 

Bodenbender,  28,  35~36,  38-39,  42-44, 
46-47 

Bonarelli,  56,  58,  98 

Brackebusch,  43 

Branner,  62-64,  7°,  93,  95-96 

Brouwer,  114 

Chamberlin,  65 

Clarke,  11,  60-61,  100 

Coleman,  23,  31,  67,  70-71,  74,  104 

Crandall,  64-65,  94 

Daly,  2 

Derby,  61,  63-64,  94,  147 
Douglas,  57,  148 
Draper,  65,  67 
Du  Toit,  94,  101,  103,  1 19 
Evans,  61 
Ferraz,  59,  74 
Fourmarier,  9 
Gothan,  55 
Gregory,  9 
Groeber,  27,  51 
Guillemain,  67,  73 
Halle,  11-12 
Harder,  65 
Haug,  11 
Hausen,  H.,  35 
Hausen,  J.,  88,  90,  93 
Hauthal,  19,  23 
Heald,  55-57 
Holdhaus,  81-82 
Holland,  148-149 
Huene,  79 
Katzer,  147-148 


Keidel,  14,  18-30,  32-35,  37,  42,  47,  49, 
51,98 
Knod,  97 

Kozlowski,  97-98,  148 

Kurtz,  36,  38-41,  89 

Leme,  59,  61,  63-64,  82,  85,  89,  95 

Lemoine,  10 

Lisbda,  94 

Lundqvist,  77 

Mather,  55-57 

Meyer,  148 

Nagera,  5 

Oliveira,  4,  67,  70,  72,  75,  81,83-84 
Orbigny,  56,  62 
Pacheco,  71,  76,  79,  83,  87 
Pastore,  5 

Penck,  36-38,  43,  35 
Rassmuss,  51-52 
Reed,  5,  35,  60,  82,  101 
Rego,  83-84 
Rimann,  53,  70 
Rogers,  27 
Schiller,  19,  20 
Seward,  11-12,  40 
Sobral,  4,  90 
Solms-Laubach,  50 
Soper,  95 

Stappenbeck,  28,  32-33,  35,  38,  43,  47~49> 

131 

Stelzner,  47 
Taylor,  1 

Walther,  3-4,  62,  66-67,  69,  73,  76,  78, 
82-84,  87,  90,  93 
Wegener,  1,  no,  115,  119 
White,  D.,  77-78,  82,  96 
White,  I.  C.,  66,  72,  80,  83-84,  86 
Windhausen,  27,  32,  51,  60,  103,  107-108 
Woodworth,  70-74,  89,  92 
Wright,  2 
Zeiller,  77,  82 


Fossils  Described  in  Appendix 


Ambocoelia  plano-convexa,  141 
Athyris,  14 1 

Aviculopecten  barrealensis,  142 
Camarophoria  cf .  mutabilis,  135 
Chonetes  granulifer,  134 

cf.  pseudo variolata,  134 
Euomphalus  subcircularis,  143 
Fenestella  aff .  perelegans,  13 1 
Hemiptychina  cf.  sublaevis,  141 
Metoptoma,  145 
Nuculana,  143 
Orbiculoidea  saltensis,  132 
Orthoceras,  145 
Pleurotomaria  advena,  143 

argentina,  144 
barrealensis,  144 
Poly pora  aff.  biseriata,  132 


Productus  curvirostris,  133 

cf.  juresanensis,  133 
lineatus,  133 

(marginifera)  cf.  echinata,  133 
spinulo-costatus, 
134 

Pseudamusium  cf  ellipticum,  142 
cf.  fibrillosum,  142 
stappenbecki,  141 
Reticularia  notica,  140 
Spirifer  barrealensis,  138;  cf.  aschensis,  139 
cf.  mexicanus,  136 
saltensis,  138 
cf.  simensis,  139 
supramosquensis,  135 
wynnei,  136 

Spiriferina  zewanensis,  139 

151 


152 


INDEX 


General 


Abaet6,  64,  70 
Accra,  10-11 
Adiantites,  36,  40 

Afro-American landmass,  1,  97, 99, 107, 109 
rupturing  of,  108,  117,  119 
Agoniatites,  100 
Agua  Suja,  70,  83 
Alethopteris,  95 
Alhuampa,  46,  58,  77 
Alkaline  rocks,  114 
Amazon  syncline,  13,  15 

valley,  Carboniferous,  57,  101,  104, 
H7-I49 

valley,  Devonian,  61,  99,  115 
Ambocoelia,  147-149 
Amygdaloid,  84,  92,  95 
Anaplophora,  45 

Andes,  14,  45,  108.  See  Cordillera 
Andesite,  48,  89 

Andine  foldings,  14,  28,  42,  107-108,  117, 
120 

Angola,  9,  16,  107,  1 14,  1 17 
Annular ia,  32,  77 
Anodontophora,  82,  150 
Araucaria,  55 
Archaean : 

Africa,  6 
Brazil,  13,  115 
Archaeopteris,  36,  40 
Areado  sandstone,  70 
Argentina : 

Carboniferous,  29-41 
compared  with  Australia,  34,  39-41, 
54,  103,  106 

Devonian,  22,  33,  35,  55,  98,  in 
Gondwana,  22-58 

glacials,  14,  22-25,  28,  30-36,  41, 

hi 

Ordovician,  19,  28,  31-32,  56 
Silurian,  18,  28,  97-98 
Arthrophycus,  19 
Assunguy  series,  59,  63,  114 
Asterocalamites,  36-37 
Asuncion,  60,  77 
Athyris,  101 
Atlantic  basin: 

central  rise,  no 
origin,  108,  119 
volcanicity,  103,  108,  no 
Atlantic  coasts,  15-16,  18,  107,  no,  117 
comparison,  1516 
Atrypa,  19 

Austral  Devonian  faunas,  6,  12,  16,  22,  99 
Australia,  comparison  with  Argentina,  41, 
.  54 

Avicula,  45 

Bahia,  13,  16,  64-65,  95~96,  107,  114 

Bahia  Blanca,  14-15,  19,  27,  107,  110-111 

Baiera,  47-48,  50 

Bajo  de  Velis,  37,  39,  43~44 

Balcarce,  19 

Bambuhy  series,  63-64,  70,  114 
Barreal,  34~35,  4 7,  ioi,  131,  148-149 
Basaltic  lavas: 

Argentina,  27,  48,  no 
Brazil,  14,  89-94,  Io6,  113 


Basaltic  lavas — continued 
South  Africa,  8,  106,  113 
Basement  rocks,  6,  13-15,  64-65,  115 
Bauru  beds,  61,  86,  96 
Beaufort  series,  8,  105 
age,  8 
flora,  8,  13 

Bello  Horizonte,  63-64 
Benguella,  9,  15 
Bermejo  series,  55-58 
age,  57 

glacials,  58,  103 
Bituminous  shales,  48,  50,  69 
B6a  Vista,  65,  114 
Bokkeveld  beds,  6,  12,  112 
Argentina,  20,  22,  in 
Bolivia,  98 
Brazil,  59,  60,  112 
Falklands,  12 
fauna,  100 
Bolivia: 

Carboniferous  fauna,  56-57,  147-149 
Carboniferous  flora,  40 
Permo-Triassic,  55-58 
Siluro- Devonian,  97-98 
Bonito  beds: 
age,  78 

Argentina,  76,  85,  92 
Brazil,  75-76,  112 
coals,  75-76 
flora,  77 
Paraguay,  77 
Uruguay,  69,  76 

Boreal,  Devonian  faunas,  16,  61,  99,  100 
Botrychiopsis,  36,  40 
Botucatu  beds,  83,  85-87,  90,  106,  113 
interbedded  lavas,  90 
Boulder: 

Beds.  See  Glacials 
Pavements,  24,  34,  102 
Brasilides,  14,  18,  62,  96 
Brazil  : 

Carboniferous  marine,  13,72,  101, 147 
Cretaceous,  61,  86,  96 
Devonian,  13-^15,  60-61,  99,  100,  112 
Permo-Triassic,  75-95 
Pre-Cambrian,  15,  64-65 
Triassic  marine,  81-82,  150 
Brazilian  Coal  Commission,  66,  75 
Bushveld  sandstone,  8,  106,  113 
Cagapava,  63,  84 
Cacheuta,  50,  54 
Calamites,  40 

Calchaquenos,  28,  31,  35,  50 
Calvinia,  7 
Camarophoria,  135 
Cameroons,  10-n,  16,  114 
Campinas,  70,  74,  76 
Cape,  geology,  6-9 
Cape  Corrientes,  1 8 
Cape  Fold-ranges,  7,  14,  19,  in 
Cape  system,  6,  12 
Capetown,  15,  62 
Caraga  quartzite,  64 
Carboniferous : 

Amazon,  13,  101,  147 


INDEX 


153 


Carboniferous — conti  nued 
Argentina,  29-41 

fossils  described,  131-149 
affinities,  147-148 
horizons,  146-147 
Asia,  1 47-1 49 
Bolivia,  56-57,  148 
Chile,  51 

Eastern  Brazil,  13,  96 
flora,  29,  37,  39-41,  100 
glacials,  Falklands,  12 

South  Africa,  7,  19,  101-102 
South  America,  15,  30-35,  72,  100 
conformity  below,  7,  23 
glaciation,  1 01-104 
movements,  6,  100 
ocean,  1 00-10 1,  104 
Peru,  100,  148 
Russia,  1 47-1 49 
South  Africa,  7 
Western  Africa,  11 
Cardiopteris,  29,  36-38,  40,  103 
Carpinterfa,  31,  36,  40 
Cave  sandstone,  8,  88,  90,  106,  113 
Ceara,  13,  16,  114 
Ceres,  7,  102 
Cerro  Bold,  37,  39,  45-46 
Bonete,  23,  25 
Largo,  63,  67,  73,  76,  81,  84 
Morado,  46 
Pelado,  32,  37-38 
Challao,  48 
Chapada,  61,  87 
Chemnitzia,  56 
Cherts,  80-82 
Chile,  Carboniferous,  51 
Liassic,  107 
Rhaetic  50 
Triassic,  50-51 
Chiropteris,  54 
Chubut,  51,  107-108 
Cladophlebis,  47,  49,  50,  54,  89 
Clanwilliam,  15,  60,  102,  m-112 
Clarkeia,  98 
Coal  measures,  8 
Coals : 

Bonito,  75-76 
Chile,  50 

Paganzo,  32,  38,  46-47,  53 
Uruguay,  76 
Cochabamba,  56 
Congo,  9,  16 

Congo  basin,  9,  95,  106,  114 
glacials,  10,  58 

Continental  disruption.  See  Displacement 
Hypothesis 
Copiapo,  50 

Cordaites,  36-37,  39-41,  77 
Cordillera,  32,  50-51,  56,  108 
Cdrdoba,  45,  53 
Corumbatahy  beds,  80-81 
Cretaceous : 

Argentina,  27,  47-48,  52,  55,  58,  no 
Brazil,  14,  16,  61,  9=5-96,  113-114 
Mediterranean  facies,  16 
Movements,  10,  51,  107,  no 
Ocean,  107,  119 
Patagonia,  14,  52 


Cretaceous — continued 

South  Africa,  9,  52,  in 
Western  Africa,  10,  16,  114 
Culm  flora,  32 
Curitiba,  71,  108 
Cuyaba,  61 

Cyzicus,  47,  50,  52,  54,  113 
Dadoxylon,  13,  47,  75,  79,  82 
Damuda  series,  8 
Devonian: 

Amazon,  13,  15,  61,  100,  115 
Argentina,  22,  33,  35,  55,  98,  hi 
Bolivia,  55,  57,  61,  97-9 8,  100 
Brazil,  14—15,  59-61,  100,  112 
change  facies,  22 
Climate,  99,  100 
Falklands,  12,  100 
faunas,  99,  100 

austral,  6,  12,  16,  22,  99 
boreal,  16,  61,  99,  100 
North  American,  99,  100,  145 
ocean,  99,  100,  115 
oscillations,  99 
Sahara,  n,  16,  99,  100,  115 
South  Africa,  6,  12,  16,  100,  111-112 
Uruguay,  60,  62 
Western  Africa,  n,  15,  100,  115 
Diamantina,  64-65,  108 
Diamonds,  59,  61,  64-65,  114-115 
Discina,  72 

Displacement  Hypothesis,  1,2,  17,  41,  9 7, 
108-110,  118,  121 
arguments  for,  103,  109,  115 
graphic  representation,  116 
Dinosaurs,  89,  113 
Dogger,  51 
Dolerites : 

age,  15,  94-  106 
Brazil,  81,  93~95,  106,  113 
Falklands,  13,  102 
South  Africa,  9,  94,  106,  113 
Dolomite: 

Argentina,  18 
Brazil,  65,  114 
Congo,  10 
South  Africa,  6 
Uruguay,  63,  67 
Drakensberg  volcanics,  8 
Durazno,  74 
Dwyka  series,  7 
age,  7 

glacials,  7,  112 

in  Argentina,  22-25,  30-36,  in 
in  Brazil,  70-72,  74-75 
in  Falklands,  12 
in  Uruguay,  67-69,  73-74 
shales,  7,  16 

White  band,  7,  78,  80,  104-105 
Brazil,  80 

Earth  movements.  See  Foldings 
Ecca  series,  7,  8,  77,  112 
age,  8,  77 
facies,  7,  8 
flora,  8,  13 

in  Argentina,  21,  26,  in 
Eocene,  10,  16 
Eogene,  107 
Equisetites,  57 


154 


INDEX 


Eremopteris,  40 
Espinago  quartzites,  64-65 
Estancia  beds,  64,  95,  114 
Estheria,  47-52,  54“55,  89,  1 13 
Estrada  Nova  group,  80-84 
age,  82,  150 
break  in,  82,  85 
fossils,  81-82,  150 
Eurydesma,  104 
Falkland  Islands,  11-13,  99,  102 
Devonian,  100,  102 
geodesic  position,  13,  16,  102,  117 
glacials,  12,  102 
tectonics,  11,  102 
Famatina,  38,  44-45,  99 
Favosites,  63 
Fenestella,  34,  56,  132 
Flora: 

Bonito,  77-78 
Carboniferous  Peru,  100 
Ecca,  8,  77 
Lafonian,  12-13 
Liassic,  55 
Molteno,  54 
Paganzo,  37-41 
Trias-Rhaetic,  49,  50,  54 
Foldings: 

Andine,  14,  28,  42,  107-108, 117,  120 
Brasilides,  14,  18,  62,  96 
Cape,  7,  14,  19,  107 
Cretaceous,  10,  51,  107,  no 
Gondwanides,  18,  26-27,  46,  52,  62, 
105,  107,  hi 
Hercynian,  27 

Permo-Triassic,  18,  27,  46,  105 
Tertiary,  14,  28,  42,  120 
Forest  sandstone,  18,  88,  91,  106,  113 
Fraile  Muerto,  63,  67-69,  73,  79,  81 
Furnas  sandstone,  59-61,  71,  98,  112 
Gangamopteris,  12,  32,  36-38 
flora,  7,  16,  77 
Glacials : 

Argentina,  14,22-25, 28,30-36,41, 1 1 1 

age,  35,  39,  4L  7§,  103,  149 
Bolivia,  58 

Brazil,  14,  70-72,  74~75 
Congo,  10 
Falklands,  12,  102 
marine,  33-35,  72,  104 
Uruguay,  67-69,  73-74 
Glaciation,  Carboniferous,  101-104,  119 
causes,  104 
centers,  101-104,  112 
striated  surfaces  below,  7,  12,  30,  33, 
35,  68,  103 

Glossopteris,  12,  36-38,  40-41,  49,  77,  82 
flora,  12,  14-16,  37,  39,  41,  44,  77, 
104-105,  1 19 

Gold  coast,  10,  15,  99,  100,  114-115 
Gondwana  beds: 

Argentina,  22-58 
Brazil,  13-14,  70-72,  74-96 
Falklands,  12 

Flora.  See  Glossopteris  Flora 
South  Africa,  7,  8 
Uruguay, 67-69,  73-76 
Gondwanaland,  1,2,  14,  78-84,  87-93,  99, 
100,  103,  105,  118-120 


Gondwanaland,  breaking  up,  107-108 
glaciation,  1 03-1 04 

Gondwanides,  18,  26-27,  46,  52,  62,  105,, 
107,  in 

Goyaz,  61,  74,  79,  82,  87,  94 
Grao  Mogul,  64-65 
Gravatahy,  72,  83 
Guandacol,  35 
Halobia,  51 
Hastimima,  79 
Hercynian  folds,  27 
High-level  gravels,  19,  26-27,  io7,  111 
age,  27,  107 
Hilario,  47 
Holcostephanus,  52 
Homalonotus,  99,  100 
Huasco,  50 
Interglacial  zones,  25 
Ipswich  series,  52,  54 
Iratf,  78,  82 

group,  16,  78-80,  84,  95,  104,  1 12 
fossils,  79 
limestones,  78 
Paraguay,  79,  82 
South  Africa,  80,  112 
Uruguay,  69,  78 
Itabirite,  64 
Itarare  series,  69,  70-74 
banded  shales,  73 
base,  68-69,  71-72,  1 12 
center  of  glaciation,  74-75 
fossils,  72 

source  of  erratics,  74 
uneven  floor,  71,  73 
Jachal,  35,  98-99,  in 
Jaguariahyva,  60,  70 
Jujuy,  43,  56 
Jurassic,  46,  55,  107 
erosion,  96 
transgression,  107 
Kalahari,  16,  91,  114 
Kaokoveld,  7,  15,  106,  112 
Karroo,  15 
basin,  66 
system,  7-9 

Argentina,  23-26,  42,  54 

Brazil  and  Uruguay,  71,  78-80,, 
85,  88-89,  92-93,  101-106, 
m-113 

Falklands,  12-13,  16 
Kimberlite,  113 
Kuibis,  6 

Kundulungu,  9,  10,  96,  114 
Kuttung  series,  40-41 
Lafonian  system,  12,  102 
Lages,  72 

Lake  Titicaca,  40,  56-57,  98,  100 
Land-bridges,  1,  no,  118 
La  Rioja,  42,  45,  99 
La  Ternera,  50,  55 
Lavras  series,  64-65 
Lebombo,  52,  106 
Leoncito  Encima,  33 
Lepidodendron,  36-37,  39,  40,  77 
Lepidophloios,  77 
Leptoccelia,  35,  99 
Liassic : 

Argentina,  51,  54 


INDEX 


155 


Liassic — continued 

Argentina  flora,  54 
volcanics,  51,  107 
Chile,  50 

Dolerites,  15,  94,  106 
Limestones : 

Argentina,  18-19 
Brazil,  61,  114 
Congo,  10 
South  Africa,  6 
Uruguay,  62-63,  6 7 
Lingula,  57,  60,  72 
Lualababeds,  9,  95 
Lubilache  beds,  9,  95,  106,  1 14 
Liideritz,  6,  15,  62,  114 
Lycopodiopsis,  77,  80,  95 
Maldonado,  63 
Mandiyuti  conglomerate,  57 
Maranhao,  13-14,  16,  94,  106,  114 
Marattiopsis,  49 
Marayes,  47,  52 
Marechal  Mallet,  81-82 
Mariental,  7,  72,  112 
Materal  formation,  57 
Matto  Grosso,  14-15,  61,  79,  89,  99,  100 
Mearim  series,  95 
Megalodus,  82,  150 
Melania,  56 
Melaphyre,  45,  51,  92 
Melilite  basalt,  113 
Melo,  63,  67,  76,  79,  81-82 
Mendoza,  45,  48-49,  52,  no 
Mesosaurus,  7,  16,  79,  105,  112 
Minas,  63 

Minas  Geraes,  13,  64 
Minas  series,  64-65 
Miocene  elevation,  27 
Molteno  beds,  8 
age,  8,  54 
flora,  8,  54 
Monograptus,  98 
Montevideo,  62,  84 
Moscovian,  35,  149 
Myophoria,  82,  150 
Nama  system,  6,  18,  62-63,  114 
Neocomian: 

Argentina,  16,  52 
Cape,  16,  52 

Neogene,  14,  16,  43,  66,  85-86 
Neuquen,  16,  52,  106-107,  no 
Neuropteridium,  36-37,  77 
Nevado  de  Famatina,  38,  44-45,  99 
New  South  Wales,  34,  39,  77,  103-104 
Nigeria,  10,  99,  114 
Noeggerathiopsis,  37 
Northern  Carboniferous  flora,  38,  40 
Olavarria,  18,  hi 
Oquita  formation,  57 
Ordn,  43 
Orbicuioidea,  60 
Ordovician : 

Argentina,  19,  28,  31-32,  56 
Bolivia,  97 
Brazil,  13-14,  62-63 
Uruguay,  62-63,  68 
Orleans  conglomerate,  72,  77 
Ouro  Preto,  64-65 
Pachycardia,  82,  150 


Paganzo  system,  14,  28-54,  112-113 
coals,  32,  38,  46-47,  53 
description,  43-54,  58 
distribution,  42-43,  46 
flora,  37-41 
folding,  31,  46 
marine  facies,  34-35 
name,  41 

overlapping,  39,  43 
stages,  43  > 

unconformity  below,  28,  30,  33,  35, 

38,  46 

volcanics,  45-46 
Palermo  shales,  75-76 
Palmeira,  78,  80,  83 

Pampean  formation,  16,  18-19,  27,  106, 

in 

ranges,  52-53 
Paraguay : 

Bonito,  77 
Devonian,  60 
Estrada  Nova,  82 
Gondwana,  60 
Iraty,  79,  82 
Triassic,  87 
Paramillo,  47-48 
Parana,  14,  59,  61,  63,  70,  83,  87 
Basin,  66-94,  io4 
Devonian,  15,  59,  60 
Parnahyba,  13 
series,  94 

Passa  Dois  series,  78-82,  85 
composite  character,  82,  85 
in  Argentina,  85 
mollusca,  82,  150 
Patagonia,  Cretaceous,  27,  55 
Patagonides,  103,  107 
Pennsylvanian,  40-41 
Peralta,  25 
Permian: 

Argentina,  14,  25-26,  43-45 
Bolivia,  57 
Brazil,  13,  94-96 
movements,  10,  18,  27,  46,  105 
South  Africa,  8,  112 
Pernambuco,  13 
Peru,  40-41,  100 

Carboniferous,  100,  148 
Petroleum,  50,  58,  80 
Phacops,  61 
Phoenicopsis,  47,  54 
Phyllotheca,  37,  46,  57-58,  77 
Piauhy,  13,  16,  94,  1 14 
Pillahuincd  beds,  19,  25-26,  31 
Pipe  amygdaloid,  48,  92,  113 
Piracicaba,  71 
Pirapora  sandstone,  96 
Plants,  fossil.  See  Flora 
Pliocene,  50,  107 
Polypora,  34 

Ponta  Grossa,  59,  60,  70-72,  75 
shales,  59,  60-61,  98,  112 
Porto  Alegre,  72,  75,  78,  83,  86-87 
Porto  Uniao,  71 
Potosi,  56,  1 01 
Potrerillos,  49,  50 
Pre- Cambrian, 

Brazil,  15,  64-65 


156 


INDEX 


Pre-  Cambri  an — continued 
Cape,  6,  15 
Southwest  Africa,  6 
Pre- Cordillera,  14,  27,  33,  41,  46 
Productus,  34,  51,  56,  101 ,  104,  147-149 
limestones,  148 
Psaronius,  80,  94-95 
Pseudamusium,  34 
Pseudomonotis,  51 
Pyramboia  group,  83,  86-87 
Quaternary,  28,  43,  117 
Quartz  prophyry,  51-52 
Queensland,  40-41,  54 
Radioactivity,  104 
Red  beds,  8,  85,  89,  113 
Reptilian  fossils,  8 
Rhacopteris,  29,  36-38,  103 
Rhaetic: 

Argentina,  42,  45-55 
Brazil,  14,  89 
Chile,  50 
Floras,  50,  54 
South  Africa,  8,  54 
Rhipidopsis,  37 
Rhodesia,  8,  88,  106 
Rhyolite,  52,  107 
Rinconada,  36 
Rio  Claro,  81-82,  94 
Rio  do  Rasto  group,  81-89,  9U  JI3 
origin,  87 

overlapping,  83-85 

Rio  Grande  do  Sul,  66,  72,  75,  81,  86,  92 
Rio  Sauce  Grande  conglomerate,  24 
Rio  (River) : 

Atuel,  27,  51,  54 
Choapa,  51 
Chubut,  51 
de  Jejenes,  31,  36-37 
de  la  Mina,  28,  31,  38 
Grande,  28-32,  36-37 
la  Plata,  15 

Negro  (Argentina),  108 
Negro  (Brazil),  70-72 
Negro  (Uruguay),  60 
Neuquen,  51 
Niger,  11,  114 
Parnahyba,  94-96 
Sao  Francisco,  13,  15,  63 
Sauce  Grande,  19,  20,  22-23,  27>  102 
Rivera,  87,  89 

Roches  moutonn£es,  7,  30,  69,  74 
Rocinha  limestone,  80,  83 
Sagenopteris,  83 
Sahara,  11,  16,  57,  99,  100 
Saharides,  10 
Saldan,  53 
Salta,  55,  58,  99 
Salt  Range,  104,  148 
Samaropsis,  78 
San  Cristobal,  76,  85,  87,  92 
San  Jorge  formation,  16,  108 
San  Juan,  28,  41-43,  101,  103-104,  110-11 
Sanogasta,  44 
San  Rafael,  27,  32 
Sao  Bento  series,  85-93 
age,  89 
area,  89 
fossils,  89 


Sao  Bento  series — continued 
origin,  88 

Sao  Jeronymo,  72,  75 

Sao  Paulo,  63,  71,  74,  76,  78-79,  81,  83, 
94,  105,  108,  1 14 

Santa  Catherina,  71,  80,  83,  86-89,  93 
system,  14,  42,  66-94 

Argentina,  76,  85,  92-93 
classification,  67 
overlapping,  72-73,  83 
Santa  Cruz: 

Bolivia,  55,  57 
Patagonia,  51,  55 
Santa  Maria,  87,  89,  91,  93 
Scaphonyx,  89 
Schizodus,  79 
Schizoneura,  46,  58 
Semionotus,  48-49,  54,  95 
Serra  Geral  eruptives,  84,  89-93 
age,  93 
petrology,  93 
thickness,  92 
Serra  Grande  series,  94 
Serrinha,  59,  70 

Sierra  Chica  de  Zonda,  28-32,  35-36,  38-39 
de  Cerro  Blanco,  46-47 
de  Cordoba,  43,  46,  53 
de  la  Huerta,  52 
del  Alto,  55-56 

de  la  Ventana,  19-27,  99,  102,  ill 
folding,  20-21,  25,  102,  hi 
shale  band,  21 
quartzites,  21,  62,  102,  111 
tillite,  22-25,  102,  hi 
de  los  Llanos,  37,  39,  44 
de  Mandiyuti,  55,  57 
de  Paganzo,  46 

de  Pillahuinco,  19,  20,  23-25,  102 

de  Sanogasta,  43 

de  Tandil,  18,  63 

de  Umango,  35,  43 

deVelazco,  37,  39 

de  Vilgo,  43 

Leone,  11,  15 

Pintada,  22,  27,  32,  51,  105,  107 
Valle  Fertil,  36,  43,  46 
Villa  Unidn,  35,  43,  46 
Sigillaria,  32,  77,  95 
Silurian,  Amazon,  13,  15,  115 
Argentina,  18,  28,  97-98 
Bolivia,  100 
ocean,  97-99 

Western  Africa,  11,  15,  115 
Solenomorpha,  81,  150 
South  Africa  compared  with  South 
America,  15-16,  19,  iio-m 
South  America,  geology,  13-14 
South  Atlantic,  108 
Southern  Flora.  See  Glossopteris  flora 
Southwest  Africa,  6,  7,  79,  93,  102,  104, 
112-114 

Sphenophyllum,  77 
Sphenopteris,  36,  40-41 
Spirifer,  34-35,  56,  60,  63,  99,  101,  104, 
1 47-1 49 

Spiriferina,  34,  56 
Stenopteris,  54 
Stephanian,  39 


INDEX 


157 


Stereosternum,  79,  80,  95 
Stormberg  series,  8,  42,  88,  113 
age,  8,  54 
divisions,  8 
transgression,  8,  113 
volcanics,  8,  52,  106 
Stromatopora,  19 
Sucre,  98 

Table  Mountain  sandstone,  6,  12,  20, 
in-112 
age,  98 

Argentina,  21,  111 
Bolivia,  98 
Falklands,  12 
glacials,  6 

Tacuaremb6,  74,  76,  79,  81,  84,  87,  89,  90 
Tasniopteris,  47-48,  50,  54,  82 
Taquara,  86-87,  90-92 
Tatuhy  group,  76 
Tertiaries : 

Argentina,  28,  52,  108,  ill 
Brazil,  13,  95,  108 
South  Africa,  9,  hi 
Western  Africa,  10 
Tertiary  foldings,  28,  107-108,  120 
high-level  gravels  19,26-27,107 
Thinnfeldia,  8,  46-48 

flora,  16,  45,  53,  106,  1 13,  1 19 
Tibagy,  59,  60,  70,  75 

sandstone,  22,  60,  112 
Tillite: 

Argentina,  14-15,  19,  22-25,  3°~3U 
33-36,  44 
Bolivia,  58 
Brazil,  70-71,  74 
South  Africa,  7 
Uruguay,  68,  73-74 
See  Glacials 
Tinogasta,  44 
Togoland,  10,  16 
Tombador  series,  64 
Tontal  series,  33 
Tornquist,  20 
Torres,  13,  66,  87,  89 
Tostado,  76,  92 
Trapiche,  37 
Traps,  86,  89 
Trias-Rhaetic : 

Argentina,  47-56,  58 


Trias-Rhaetic — continued 

Brazil,  13-14,  61,  67,  80-93 
Chile,  50 
Patagonia,  51,  55 
South  Africa,  8,  no 
Uruguay,  80-91 
Triassic: 

Argentina,  45-46,  92 
Bolivia,  56 

Brazil,  13-14,  61,  67,  80-91,  95 
climate,  87-91,  106,  113,  119 
Congo,  9 

Marine,  45,  50,  81-82,  150 
tuffs,  51-52 

unconformity  below,  8,  14-15,  27,  32, 
42,  46-47,  50,  67,  74,  83-85,  105, 
no 

volcanics,  27,  51-52,  85,  94,  119 
Trigonia,  52 
Tropidoleptus,  60 
Tuberao  series,  75-77,  84 
Tucumdn,  43,  55 
Uitenhage,  52,  no 
fauna,  16,  52 

Argentina,  16,  52,  in 
Uralian,  35,  40,  56 
Uruguay: 

Devonian,  60,  62 
Gondwana : 
coals,  76 

glacials,  67-69,  73-74 
volcanics,  84,  90-93 
Ordovician,  62-63,  68 
Uspallata,  32,  49,  51 
Volcanics: 

Liassic,  51,  107 
Paganzo,  45-46 
Serra  Geral,  89-93 

Argentina,  85,  92-93 
Stormberg,  8,  93-94 
Triassic,  48,  51-52,  85,  90-94,  119 
Wegener’s  Hypothesis.  See  Displacement 
Hypothesis 
Western  Africa,  10-1 1 
Westphalian,  39,  40 
White  band,  7,  78,  80,  112 
Witteb erg  series,  7,  12,  102 
Argentina,  20,  in 
Falklands,  12 


PLATES 


I.  Folded  Devonian  quartzites,  Sierra  de  la  Ventana. 

II.  A.  Shale  band  in  Devonian  quartzites,  Sierra  de  la  Ventana;  B.  Cleavage  in  til- 
lite,  Sierra  de  la  Ventana. 

III.  A.  Tertiary  “high-level  gravels,’'  Sierra  de  la  Ventana;  B.  Lower  glacial  zone, 

Sierra  Chica  de  Zonda,  San  Juan. 

IV.  A.  Glaciated  surface  beneath  lowest  glacial  zone,  San  Juan;  B.  Lowest  glacial 

zone,  Sierra  Chica  de  Zonda,  San  Juan. 

V.  A .  Second  glacial  zone,  Sierra  Chica  de  Zonda,  San  Juan;  B.  Second  glacial  zone, 
Sierra  Chica  de  Zonda,  San  Juan. 

VI.  Second  glacial  zone,  Sierra  Chica  de  Zonda,  San  Juan. 

VII.  A.  Second  glacial  zone,  Sierra  Chica  de  Zonda,  San  Juan;  B.  Dome  in  Paganzo 
beds,  Carpinterla,  San  Juan. 

VIII.  A.  Dome  in  Carboniferous  beds,  Barreal,  San  Juan;  B.  Paganzo  beds,  Bajo  de 
Velis,  San  Luiz. 

IX.  Triassic  beds,  Barreal,  San  Juan. 

X.  A.  Tree-trunks  in  Triassic  beds,  Paramillo  de  Uspallata;  B.  Triassic  beds, 
Marayes,  San  Juan. 

XI.  A.  Triassic  conglomerates,  Saldan,  Cordoba;  B.  Triassic  conglomerates,  Capilla 
del  Monte,  Cordoba. 

XII.  A.  Devonian  Furnas  sandstone,  Ponta  Grossa,  Parana;  B.  Rio  do  Rasto  sand¬ 

stones,  Taquara,  Porto  Alegre. 

XIII.  Carboniferous  fossils,  Barreal,  Argentina. 

XIV.  Carboniferous  fossils,  Barreal,  Argentina. 

XV.  Carboniferous  fossils,  Barreal,  Argentina. 

XVI.  Carboniferous  fossils,  Barreal,  Argentina . 


m  l! BRMtf  M  THt 

27  1928 

UNlVttlSMY  01  tU'N°*s 


158 


N 


Carnegie  Inst.  Wash.  Pub.  381 


PLATE  I 


Folded  Devonian  quartzites  north  of  the  Cerro  Naposta  Grande,  looking  east 

From  a  photograph  by  Dr.  R.  Beder 


Carnegie  Inst.  Wash.  Pub.  381 


PLATE  II 


A — Shale  band  in  quartzites  of  the  Sierra  de  la 
Ventana  gorge  below  the  Tres  Picos 


B — Cleavage  in  tillite,  railway  cutting  a  little  northeast  of  Sierra  de  la  Ventana  station 


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PLATE  III 


A — Tertiary  “  high-level 


gravels"  on  folded  Devonian  beds,  west  side  of  the  Arroyo  San 
Bernardino,  Sierra  de  la  Ventana 


B — Lower  glacial  zone,  immediately  to  the  north  of  the  Rio  Grande,  Sierra  Chica  de  Zonda, 

San  Juan 


Carnegie  Inst.  Wash.  Pub.  381 


PLATE  IV 


A — Glaciated  surface  of  Ordovician  limestone  beneath  lowest  glacial  zone,  a  little  north  of 
the  Rio  Grande,  Sierra  Chica  de  Zonda,  San  Juan;  the  hammer  indicates  the  direction 
of  the  glacial  striae 


B — The  lowest  glacial  zone,  resting  on  tilted  Palaeozoics,  followed  by  plant-bearing  shales 
crowned  with  sandstones,  a  little  north  of  the  Rio  Grande,  Sierra  Chica  de  Zonda, 
San  Juan 


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PLATE  V 


A — Second  glacial  zone,  a  little  north  of  the  Rio  Grande,  Sierra  Chica  de  Zonda,  San  Juan. 
The  dark  tillite  forms  the  central  peak  and  is  sandwiched  between  well-stratified  beds; 
the  third  glacial  zone  forms  the  point  on  the  extreme  left 


B — Second  glacial  zone,  Arroyo  de  Jejenes,  San  Juan.  Below  are  sandstones,  followed  by 
the  glacials  with  lens  of  sandy  material  and  overlain  by  sandstones  which  form  the 
summit  of  the  cliff 


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The  second  glacial  zone,  Arroyo  de  Jejenes,  San 
Juan,  showing  lenticular  band  of  sandy  material 


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PLATE  VI 


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PLATE  VII 


A— The  second  glacial  zone,  Arroyo  de  Jejenes,  San  Juan,  showing  practically 

unstratified  tillite 


B— Dome  in  Paganzo  beds,  followed  by  tilted  Calchaquenos  and  overlain  by  horizontal 

Quaternary  gravels;  west  of  Carpinteria,  San  Juan 


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PLATE  VIII 


A — Dome  in  Carboniferous  beds  near  Quebrada  del  Salto,  Barreal,  San  Juan,  showing  in 
foreground  boulder  shales  and  fossiliferous  shales,  followed  by  sandstones  forming 
the  hills  in  the  background 


B— Plant-bearing  Paganzo  beds,  Bajo  de  Velis,  Sierra  de  San  Luiz.  The  range  in  the  back¬ 
ground  is  made  of  crystalline  rocks 


>  • 


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PLATE  IX 


A — Triassic  plant-bearing  strata  of  Stage  IV,  Quebrada  del  Jarillal,  Barreal; 

on  extreme  right  beds  of  Stage  V 


B — Triassic  beds  of  Stage  IV,  overlain  by  the  red  conglomeratic  strata  of  Stage  V 

Quebrada  del  Salto,  Barreal,  San  Juan 


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PLATE  X 


A — Tree  trunks  standing  erect  in  Triassic  volcanic  ash,  Paramillo  de  Uspallata 


B — Tilted  sandstones  and  conglomerates  of  the  coal-bearing  section  of  Stage  IV,  Carrizal 

near  Marayes,  Sierra  de  la  Huerta,  San  Juan 


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PLATE  XI 


B — Triassic  conglomeratic  sandstones,  Los  Terrones,  near  Capilla  del  Monte 

Sierra  de  Cordoba 


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PLATE  XII 


A — Devonian  Furnas  sandstone,  showing  current-bedding.  East  of  Ponta  Grossa,  Parana 


B — Rio  do  Rasto  "  millet-seed  "  sandstones,  municipal  quarry,  Taquara,  near  Porto  Alegre. 
The  marked  dip  from  left  to  right  is  due  to  false  bedding,  the  formation  being  actually 
horizontal 


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PLATE  XIII 


Carboniferous  Fossils,  Barreal,  Argentina 

(i)  Orbiculoidea  saltensis  sp.  nov.  (7335),  upper  valve.  X  1.5.  (2)  Productus  ( Marginifera ) 

spinulo-costatus  Abich  var.  nov.  peregrina  (7374),  pedicle-valve.  X  1.25.  (3)  Spiriferina  zewanensis 
Diener  (7312),  pedicle-valve.  X  1.5.  (4a,  46)  Productus  curvirostris  Schellwien  var.  nov.  barrealensis 
(7315),  pedicle-valve,  a,  top  view;  b,  front  view.  X  2.  (5)  Hemiptychina  cf.  sublcevis  Waagen  (7300), 

pedicle-valve.  X  3-  (6)  Choneles  granulifer  Owen  (7319),  pedicle-valve  (shell  partly  wanting).  X  1.5. 

(7)  Nuculana  ( Leda )  cf.  bellistriata  Stevens  (7339),  internal  cast.  X  2.  (8a,  8 b)  Reticularia  notica  sp.  nov. 

(7326);  a,  pedicle-valve.  X  1.5;  b,  portion  of  shell.  X  8.  (9)  Productus  lineatus  Waagen  (7365),  side  view, 

pedicle-valve.  X  2.  (10)  Reticularia  notica  sp.  nov.  (7445),  pedicle-valve.  X  1.5.  ( 1 1 )  Pseudamusium 

stappenbecki  sp.  nov.  (7291),  left  valve.  X  1.5.  (12)  Pseudamusium  cf.  elliplicum  (Phillips)  (7304),  left 

valve.  X  1.5.  (13)  Pseudamusium  stappenbecki  sp.  nov.  (7290),  right  valve.  X  1.5.  (14)  Aviculopecten 

barrealensis  sp.  nov.  (7362),  left  valve.  X  4. 


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PLATE  XIV 


7b  8b 

Carboniferous  Fossils,  Barreal,  Argentina 

(i)  Spirifer  of.  supramosquensis  Nikitin  (7316),  pedicle-valve.  X  1.25.  (2)  Spirifer  barrealensis 

sp.  nov.  (7371),  pedicle-valve.  X  1.5.  (3)  Spirifer  mexicanus  Shumard  var.  nov.  neolropica  (7366),  pedicle- 
valve.  X  1.25.  (4)  Spirifer  mexicanus  Shumard  var.  nov.  neotropica  (7375),  pedicle-valve.  X  1.25.  (5) 

Spirifer  aff.  rajah  Salter  (7317),  pedicle-valve  (anterior  part  bent  underneath).  X  1.5.  (6)  Spirifer 

( Martinia )  cf.  simensis  Tschernyschew  (7363),  pedicle-valve.  X  1.5.  (7 a,  7b)  Spirifer  Wynnei  Waagen  var. 
nov.  argenlina  (7309),  a  brachial  valve,  X  1.25;  b  front  view.  X  1.25.  (8a,  8 b)  Spirifer  saltensis  sp.  nov. 

(7296);  a,  pedicle-valve.  X  1.5;  b,  brachial  valve.  X  i.S- 


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PLATE  XV 


3  c 


Carboniferous  Fossils,  Barreal,  Argentina 

(i)  Euomphalus  subcircularis  Mansuy  (7328),  base.  X  1.  (2)  Euomphalus  subcircularis  (7344) 

apical  surface.  X  1.25.  (3a,  3 b,  3c)  Pleurotomaria  argentina  sp.  nov.  (7334);  a,  b,  side-views.  X  1.5;  c,  por¬ 
tion  of  base.  X  6.  (4)  Euomphalus  subcircularis  (7322),  apical  surface.  X  1.25.  (5)  Pleurotomaria 

advena  sp.  nov.  (7355)-  X  i-5- 


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PLATE  XVI 


Carboniferous  Fossils,  Barreal,  Argentina 

Pleurotomaria  barrealensis  sp.  nov.  (7323) ;  a,  side  view.  X  1.5;  b,  base,  X  1.5. 


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